JC-NRLF 


AND  ITS  PRODUCTS 


AND  WOLL, 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


i   ; 


DR.  S.  M.  BABCOCK 
Inventor  of  the  Babcock  Milk  Test 


TESTING  MILK 

ITS  PRODUCTS 


A  MANUAL  FOR  DAIRY  STUDENTS,  CREAMERY-  AND  CHEESE 

FACTORY  OPERATORS,  FOOD  CHEMISTS,  AND 

DAIRY  FARMERS 


E.  H.  FARRINGTON         and        F.  W.  WOLL 

Professor  in  Charge  of  Dairy  School  Professor  of  Agr'l  Chemistry 

Of  the  University  of  Wisconsin 


lUitb  ailuBtratfons 


EIGHTEENTH  REVISED  AND  ENLARGED  EDITION 


MADISON,  WIS. 
MENDOTA  BOOK  COMPANY 

1908 
ALL,   RIGHTS  RESERVED 


COPYRIGHT,  1897, 1899, 1901,  1904  AND 
BY  E.  H.  FARRINGTON  AND  F.  W.  WOLL 


CANTWELL  PRINTING  COMPANY 
MADISON,  WIS. 


Preface  to  First  EcTition. 


The  present  volume  is  intended  for  the  use  of  dairy  students, 
factory  operators,  dairymen,  food  chemists,  and  others  interested 
in  the  testing  or  analysis  of  milk  and  its  products.  The  subject 
has  been  largely  treated  in  a  popular  manner;  accuracy  and 
clearness  of  statement,  and  systematic  arrangement  of  the  sub- 
ject matter  have,  however,  been  constantly  kept  in  mind.  The 
aim  has  been  to  make  the  presentation  intelligible  to  students, 
with  no  further  training  than  a  common-school  education,  but 
their  work  will  naturally  be  greatly  lightened  by  the  aid  of  an 
able  teacher. 

Complete  directions  for  making  tests  of  milk  and  other  dairy 
products  are  given;  difficulties  which  the  beginner  may  meet 
with  are  considered  in  detail,  and  suggestions  offered  for  avoid- 
ing them.  It  is  expected  that  a  factory  operator  or  practical 
dairyman,  by  exercising  common  sense  and  ordinary  care,  can 
obtain  sufficient  knowledge  of  the  subject  through  a  study  of 
the  various  chapters  of  this  book  to  make  tests  of  milk,  cream, 
etc.,  even  if  hei  has  had  no  previous  experience  in  this  line. 

For  the  benefit  of  advanced  dairy  students  who  are  somewhat 
familiar  with  chemistry  and  chemical  operations,  Chapter  XIV 
has  been  added  giving  detailed  instructions  for  the  complete 
chemical  analysis  of  milk  and  other  dairy  products.  The  detec- 
tion of  preservatives  and  of  artificial  butter  or  filled  cheese  has 
also  been  treated  in  this  connection. 

As  the  subject  of  milk  testing  is  intimately  connected  with 
the  payment  for  the  milk  delivered  at  butter-  and  cheese  fac- 
tories, and  with  factory  dividends,  a  chapter  has  been  devoted 
to  a  discussion  of  the  various  systems  of  factory  book-keeping, 
and  tables  greatly  facilitating  the  work  of  the  factory  secretary 
or  bookkeeper  have  beein  prepared  and  are  included  in  the 
Appendix. 

Madison,  Wis.,  October  1,  1897. 


31082 


Preface  to  Eighteenth  Edition. 


Each  year  that  passes  brings  some  valuable  contributions  to 
our  knowledge  of  the  subjects  treated  in  this  book  and  a  fre- 
quent revision  of  it  is  therefore  desirable.  The  present  edition 
contains  descriptions  of  methods  and  apparatus  that  have  stood 
the  test  of  actual  use  during  the  past  few  years;  the  new  infor- 
mation published  since  the;  last  revision  of  the  book,  has  been 
carefully  sifted,  and  what  was  deemed  of  sufficient  importance 
has  been  incorporated  in  such  detail  as  the  scope  of  the  book 
permitted;  many  changes  and  additions  suggested  by  the  expe- 
rience of  the  authors  have  also  been  introduced. 

The  book  has,  in  brief,  been  subjected  to  a  renewed  critical 
examination  and  careful  revision.  Among  thei  new  subjects  dis- 
cussed in  this  edition  may  be  mentioned:  Analysis  of  ice  cream; 
estimation  of  water  in  butter  by  thei  Gray,  Patrick,  Irish,  Dean, 
and  Wisconsin  oven  methods;  the  Marschall  acid  test;  the  McKay 
and  Michels'  sampling  tubes;  milk  and  cream  overrun;  the  Gott- 
lieb method -of  determining  fat  in  milk;  the  Hart  casein  test; 
standards  for  Babcock  glassware,  etc.  The  general  adoption  of 
the  book  as  a  text  or  reference  book  in  American  dairy  schools, 
as  well  as  the  favorable  reception  which  it  has  been  accorded  by 
the  dairy  public  in  general,  will,  it  is  hoped,  be  further  justified 
by  the  present  revision. 

Acknowledgment  is  due  to  the  following  parties  for  loan 
of  electrotypes,  viz.:  Creamery  Pkg.  Mfg.  Co.,  Chicago,  111.; 
Vermont  Farm  Machine  Co.,  Bellows  Falls,  Vt. ;  Dairy  Specialty 
Co.,  West  Chester,  Pa.;  D.  H.  Burrell  &  Co.,  Little  Falls,  N.  Y.; 
De  Laval  Separator  Co.,  New  York  City;  Henry  Tromner,  Phila- 
delphia, Pa.;  Torsion  Balance  Co.,  New  York  City;  Bausch  & 
Lomb  Opt.  Co.,  Eochester,  N.  Y.;  J.  G.  Cherry,  Cedar  Eapids, 
la.;  Marschall  Dairy  Laboratory,  Madison,  Wis.,  and  Interna- 
tional Instrument  Co.,  Cambridge,  Mass. 

Madison,    Wis.,   Jan.   4,    1908. 


Table  of  Contents. 


PAGE 

Introduction 1 

Chap.  I.    COMPOSITION  OF  MILK  AND  ITS  PRODUCTS  ...       10 

Composition  of  milk:  Water.  Fat.  Casein  and  albu- 
men. Milk  sugar  (lactose).  Ash.  Other  components. 
Colostrum  milk.  Composition  of  milk  products. 

Chap.  II.    SAMPLING  MILK 23 

Sweet  milk.     Partially  churned  milk.     Sour  milk.     Frozen 
milk. 
Chap.  III.     THE  BABCOCK  TEST — MILK 28 

A.  Directions  for  making  the  test: 

Sampling.  Adding  acid.  Mixing  milk  and  acid.  T^hirl- 
ing  bottles.  Adding  water.  Measuring  the  fat. 

B.  Discussion  of   the  details  of  the  test: 

1.  Glassware.     Test  bottles.     Marking  test  bottles.     Ap- 
paratus   for    cleaning     test    bottles.      Pipettes.     "Fool    pi- 
pettes. "     Acid  measures.     The   Swedish  acid-bottle.      Cali- 
bration  of    glassware:      With   water;    with    mercury.      The 
Trowbridge  method  of  calibration.    Calibration  of  skim-milk 
and  cream  test  bottles,  of  pipettes  and  acid  cylinders. 

2.  Centrifugal    machines.      Speed   required    for    the   com- 
plete   separation    of    the    fat.      Ascertaining    the    necessary 
speed  of  testers.     Hand   testers.     Power   turbine  and   elec- 
trical testers. 

3.  Sulfuric    acid.      Testing    the    strength    of    acid.      The 
Swedish  acid  tester.     Thei  color  of  the  fat  column  an  index 
to  the  strength  of  the  acid  used.     Influence  of  temperature 
on  the  separation  of  fat. 

4.  Water  to  be  used  in  the  Babcock  test.     Reservoir  for 
water.  . 

5.  Modifications  of  the  Babcock  test.     The  Russian  milk 
test.       Bartlett's     modification.       Siegf  eld's     modification. 
Bausch   and  Lomb  centrifuge. 

Chap.  IV.    THE  BABCOCK  TEST — CREAM 75 

Errors  of  measuring  cream.  Weighing  cream  for  test- 
ing. Cream-test  bottles.  The  Winton  cream  bottle,  'ixie 
bulb-necked  cream  bottle.  Cream-weighing  scales.  Measur- 
ing cream  for  testing.  Use  of  milk  test  bottle.  Use  of 
5  cc.  pipette.  Proper  readings  of  cream  tests. 
Chap.  V.  THE  BABCOCK  TEST — OTHER  MILK  PRODUCTS  .  88 

Skim  milk,  butter  milk  and  whey.  The  double-necked 
test  bottle.  The  Wagner  test  bottle.  The  double-sized 
skim  milk  bottle.  Butter.  Cheese.  Condensed  milk.  Ice 
cream. 


vi  Testing  Milk  and  Its  Products. 


Chap.  VI.  THE  LACTOMETER  AND  ITS  APPLICATION     .      .     .     100 

The  Quevenne  lactometer.  Influence  of  temperature. 
N.  Y.  Board  of  Health  lactometer.  Reading  the  lactome- 
ter. Time  of  taking  lactometer  readings.  Influence  of  solid 
preservatives  on  lactometer  readings.  Cleaning  lactometers. 
Testing  the  accuracy  of  lactometers.  Calculation  of  milk 
solids.  Adulteration  of  milk.  Legal  standards.  The  spe- 
cific gravity  of  milk  solids.  Calculation  of  extent  of  adul- 
teration: Skimming.  Watering.  Watering  and  skimming. 

Chap.  VII.    TESTING  THE  ACIDITY  OF  MILK  AND  CREAM     .     117 

Cause  of  acidity  in  milk.  Methods  of  testing  acidity. 
Manns7  test.  Devarda's  acidimeter.  The  alkaline-tablet 
test.  Determination  of  acidity  in  sour  cream.  Spillman's 
cylinder.  The  Marschall  acid-test.  Rapid  estimation  of  the 
acidity  of  apparently  sweet  milk  and  cream.  Detection  of 
boracic-acid  preservatives  in  milk.  "Alkaline  Tabs. " 

Chap.  VIII.    TESTING  THE  PURITY  OF  MILK 135 

The  Wisconsin  curd  test.  The  fermentation  test.  The 
Monrad  rennet  test.  The  Marschall  rennet  test. 

Chap.  IX.   TESTING  MILK  ON  THE  FARM 140 

Variations  in  milk  of  single  cows.  Number  of  tests  re- 
quired during  a  period  of  lactation  in  testing  cows.  When 
to  test  a  cow.  Sampling  milk  of  single  cows.  Composite 
samples.  Variations  in  herd  milk.  Influence  of  heavy  grain 
feeding  and  of  pasture  on  the  quality  of  milk.  Method  of 
improving  the  quality  of  milk. 

Chap.  X.   COMPOSITE  SAMPLES  OF  MILK 158 

Methods  of  taking  composite  samples.  Use  of  tin  dip- 
per. Drip  sample.  The  Scovell,  McKay,  and  Michels'  sam- 
pling tubes.  One-third  sample  pipette.  Preservatives  for 
composite  samples.  Care  of  composite  samples.  Fallacy 
of  averaging  percentages.  A  patron 's  dilemma. 

Chap.  XI.    CREAM  TESTING  AT  CREAMERIES 175 

The  space  system.  The  oil-test  churn.  The  Babcock  test 
for  cream.  Gathering  and  sampling  hand-separator  cream. 
Chap.  XII.  CALCULATION  OF  BUTTER-  AND  CHEESE  YIELD  .  186 

A.  Calculation  of  yield   of   butter:     Butter-fat  test   and 
yield  of  butter.    Variations  in  composition  of  butter.    Over- 
run of  churn  over  test.     Factors  influencing  the  overrun  for 
milk  and  for  cream.     Calculation  of  milk  and  cream  over- 
run.    Conversion  factor  for  butter  fat.     Butter  yield  from 
milk   of   different  richness.     Use  of  butter   chart.     Use   of 
overrun   table. 

B.  Calculation  of  yield  of  cheese:     From  fat.     From  sol- 
ids not  fat  and  fat.     From  casein  and  fat. 


Table  of  Contents.  vii 


Chap.  XIII.    CALCULATING  DIVIDENDS 202 

A.  Calculating     dividends     at     creameries:       Proprietary 
creiameries.      Co-operative   creameries.      Illustrations   of    cal- 
culations of  dividends.     Paying  for  butter  delivered.     Bela- 
tive-value   tables.     Milk-   and  cream  dividends. 

B.  Calculating    dividends    at    &iees&   factories:      Proprie- 
tary factories.     Co-operative  factories. 

Chap.  XIV.    CHEMICAL  ANALY^S  OP  MILK  AND  ITS  PROD- 
UCTS     .      .      ^ 215 

Milk.  The  Gottlieb  method;  Hart's  casein  test.  Cream, 
skim  milk,  butter  milk,  whey,  condensed  milk. 

Butter.  Complete  analysis  in  the  same  sample.  Eapid 
estimation  of  water  in  butter:  Gray's,  Patrick's,  Irish's, 
Dean's,  and  Wisconsin  high-pressure  oven  methods.  A  prac- 
tical method  of  estimating  salt  in  butter.  Detection  of  arti- 
ficial butter.  Eeichert-Wollny  method  (Volatile  acids). 
Tests  for  the  detection  of  oleomargarine  and  renovated  but- 
ter: The  boiling  test.  The  Waterhouse  test. 

Cheese.  Detection  of  oleomargarine  cheese  (" Filled" 
cheese). 

Tests  for  adulteration  of  milk  and  cream.  Detection  o£- 
coloring  matter,  and  of  pasteurized  milk  or  cream.  Boiled 
milk.  Gelatine  and  starch  in  cream.  Macroscopic  impuri- 
ties. Detection  of  preservatives  in  dairy  products:  Boracic 
acid.  Bi-carbonate  of  soda.  Fluorids.  Salicylic  acid. 
Formaldehyde. 

Government  standards  of  purity  for  milk  and  its  prod- 
ucts. Standards  for  Babcock  glassware. 

Appendix 254 

Table  I.     Composition   of  milk   and  its  products. 
Table  II.     State  and  city  standards  for  dairy  products. 
Table    III.      Quevenne    lactometer   degrees    corresponding 
to  the  scale  of  the  N.  Y.  Board  of  Health  lactometers. 

Table  IV.    Value  of    100S~100  for  specific  gravities  from 

1.019  to   1.0369. 

Table  V.     Correction  table  for  specific  gravity  of  milk. 

Table  VI.  Per  cent,  of  solids  not  fat,  corresponding  to 
0  to  6  per  cent,  of  fat  and  lactometer  readings  of  26  to  36. 

Directions  for  the  use  of  Tables  VII,  VIII,  IX  and  XI. 

Table  VII.  Pounds  of  fat  in  1  to  10,000  pounds  of  milk 
testing  3  to  5.35  per  cent. 

Table  VIII.  Pounds  of  fat  in  1  to  1,000  Ibs.  of  cream 
testing  12.0  to  50.0  per  cent.  fat. 

Table  IX.  Amount  due  for  butter  fat,  in  dollars  and 
cents,  at  12  to  25  cents  per  pound. 

Table  X.     Eelative-value   tables. 


viii  Testing  Milk  and  Its  Products. 

PAGE 

Table  XI.  Butter  chart,  showing  calculated  yield  of 
butter,  in  pounds,  from  1  to  10,000  pounds  of  milk  testing 
3.0  to  5.3  per  cent,  of  fat. 

Table  XII.  Overrun  table,  showing  pounds  of  butter 
from  100  pounds  of  milk. 

Table  XIII.  Yield  of  cheese,  corresponding  to  2.5  to  6 
per  cent,  of  fat,  with  lactometer  readings  of  26  to  36. 

Table  XIV.  Comparisons  of  Fahrenheit  and  Centigrade 
(Celcius)  thermometer  scales. 

Table  XV.  Comparison  of  metric  and  customary  weights 
and  measures. 

Suggestions  regarding  the  organization  of  co-operative 
creameries  and  cheese  factories. 

Constitution  and  by-laws  for  co-operative  factory  asso- 
ciations. 

Index 286 


Testing  Milk  and  its  Products 


INTRODUCTION. 

The  need  of  a  rapid,  accurate  and  inexpensive  method 
of  determining  the  amount  of  butter  fat  in  milk  and 
other  dairy  products  became  more  and  more  apparent, 
in  this  country  and  abroad,  with  the  progress  of  the 
dairy  industry,  and  especially  with  the  growth  of  the 
factory  system  of  butter  and  cheese  making  during  the 
last  few  decades.  So  long  as  each  farmer  made  his  own 
butter  and  sold  it  to  private  customers  or  at  the  village 
grocery,  it  was  not  a  matter  of  much  importance  to 
others  whether  the  milk  produced  by  his  cows  was  rich 
or  poor.  But  as  creameries  and  cheese  factories  mul- 
tiplied, and  farmers  in  the  dairy  sections  of  our  coun- 
try became  to  a  large  extent  patrons  of  one  or  the  other 
of  these,  a  system  of  equitable  payment  for  the  milk 
or  cream  delivered  became  a  vital  question. 

i.  Nearly  all  the  creameries  in  existence  in  this  coun- 
try up  to  about  1890  were  conducted  on  the  cream- 
gathering  plan:  the  different  patrons  creamed  their 
milk  by  the  gravity  process,  and  the  cream  was  hauled 
to  the  creamery,  usually  twice  or  three  times  a  week, 
where  it  was  then  ripened  and  churned.  The  patrons 
were  paid  per  inch  of  cream  furnished.  This  quantity 

was  supposed  to  make  a  pound  of  butter,  but  cream 
i 


2  Testing  Milk  and  Its  Products. 

from  different  sources,  or  even  from  the  same  sources 
at  different  times,  varies  greatly  in  butter-producing 
capacity,  as  will  be  shown  under  the  subject  of  cream 
testing  (2031).  The  system  of  paying  for  the  number 
of  creamery  inches  delivered  could  not  therefore  long 
give  satisfaction. 

The  proposition  to  take  out  a  small  portion,  a  pint  or 
half  a  pint,  of  the  cream  furnished  by  each  patron,  and 
determine  the  amount  of  butter  which  these  samples 
would  make  on  being  churned  in  so-called  test  churns, 
found  but  a  very  limited  acceptance,  on  account 'of  the 
labor  involved  and  the  difficulty  of  producing  a  first-class 
article  from  all  the  small  batches  of  butter  thus  ob- 
tained. 

2.  The  introduction  of  the  so-called  oil  test  churn  in 
creameries,  which  followed  the  creamery-inch  system, 
marked  a  decided  step  in  advance,  and  it  soon  came 
into  general  use  in  gathered-cream  factories  (202).  In 
this  test,  glass  tubes  of  about  %  inch  internal  diameter 
and  nine  inches  long,  are  filled  with  cream  to  a  depth 
of  five  inches,  and  the  cream  is  churned ;  the  tubes  are 
then  placed  in  hot  water,  and  the  column  of  melted 
butter  formed  at  the  top  is  read  off  by  means  of  a  scale 
showing  the  number  of  pounds  of  butter  per  creamery 
inch  corresponding  to  different  depths  of  melted  but- 
ter. While  the  oil  test  is  capable  of  showing  the  differ- 
ence between  good  and  poor  cream,  it  is  not  sufficiently 
accurate  to  make  satisfactory  distinctions  between  dif- 
ferent grades  of  good  and  poor  cream.2  As  a  result, 

1  Refers  to  paragraph  numbers. 

9  Wlscon-in  experiment  station,  bulletin  12.    (Soonlso  umlor203.) 


Introduction.  3 

perfect  justice  cannot  be  done  to  different  patrons  of 
creameries  where  payments  for  cream  delivered  are 
made  on  the  basis  of  this  test. 

3.  In  cheese  factories,  and  since  the  introduction  of 
the  centrifugal  cream  separator,  in  separator  creamer- 
ies, the  problem  of  just  payment  for  the  milk  furnished 
by  different  patrons  was  no  less  perplexing  than  in  the 
case  of  gathered-cream  factories.     By  the  pooling  sys- 
tem generally  adopted,  each  patron  received  payment 
in  proportion  to  the  number  of  pounds  of  milk  deliv- 
ered, irrespective  of  its  quality.   Patrons  delivering  rich 
milk  naturally  will  not  be  satisfied   with  this  system 
when  they  find  that  their  milk  is  richer  than  that  of 
their   neighbors.     The  temptation  to   fraudulently   in- 
crease the  amount  of  milk  delivered  by  watering,  or  to 
lower  its  quality  by  skimming,  will  furthermore  prove 
too  strong  for  some  patrons ;  the  fact  that  it  was  diffi- 
cult to  prove  any  fraud  committed,  from  lack  of  a  re- 
liable and  practical  method  of  milk  analysis,  rendered 
this  pooling  system  still  more  objectionable. 

4.  As  another  instance  in  which  the  need  of  a  simple 
test  for  determining  the  fat  content  of  different  kinds 
of  milk  was  strongly  felt,  may  be  mentioned  the  case  of 
private  dairymen  and  breeders  of  dairy  cattle  who  de- 
sired to  ascertain  the  butter-producing  capacities  of  the 
individual   cows  in  their  herds.     The  only  manner  in 
which   this    could    be    done,    was   by   the    cumbersome 
method  of  trial  churnings :  by  saving  the  milk  of  the 
cow  to  be  tested,  for  a  day  or  a  week,  and  churning 
separately  the  cream  obtained.     This  requires  a  large 
amount   of  work  when  a   number  of   cows   are   to  be 


4  Testing  Milk  and  Its  Products. 

tested,  and  can  not  therefore  be  done  except  in  com- 
paratively few  cases,  with  cows  of  great  excellence  or 
by  farmers  having  abundant  hired  help. 

5.  Introduction  of  milk  tests.  The  first  method 
which  fulfilled  all  reasonable  demands  of  a  practical 
and  reliable  milk  and  cream  test  was  the  Babcock  test, 
invented  by  Dr.  S.  M.  Babcock,  of  the  Wisconsin  agri- 
cultural experiment  station.  A  description  of  the  test 
was  first  published  in  July,  1890,  as  bulletin  No.  24  of 
that  Station,  entitled:  A  new  method  for  the  estimation 
of  fat  in  milkf  especially  adapted  to  creameries  and 
cheese  factories.  This  test,  which  is  now  known  and 
adopted  in  all  parts  of  the  world  where  dairying  is  an 
important  industry,  was  not,  however,  the  first  method 
proposed  for  this  purpose  which  could  be  successfully 
operated  outside  of  chemical  laboratories.  It  was  pre- 
ceded by  a  number  of  different  methods,  the  first  one 
published  in  this  country  being  Short's  method,  in- 
vented by  Mr.  F.  G.' Short  and  described  in  bulletin 
No.  16  of  Wisconsin  experiment  station  (July  1888). 

6.  Short's  test.     In   this   ingenious   method,    a   certain   quan- 
tity of   milk    (20   cc.1)    was  boiled   with  an  alkali   solution    and 
afterwards  with  a  mixture  of  sulfuric  and  acetic  acids;   a  layer 
of  insoluble  fatty  acids  separated  on  top  of  the  liquid  and  was 
brought  into  the  graduated  neck  of  the  test  bottles  by. addition 
of  hot  water;  the  reading  gave  the  per  cent,  of  fat  in  the  sam- 
ple of  milk  tested. 

Short's  method  did  not  find  very  wide  application,  both  be- 
cause it  was  rather  lengthy  and  its  manipulations  somewhat  dif- 
ficult for  non-chemists,  and  because  several  other  methods  were 
published  shortly  after  it  had  been  given  to  the  public. 

7.  Other  milk  tests.     Of    these    may    be    mentioned,    besides 
the   Babcock    test   already   spoken    of,    the   Failyer   and    Willard 

i  See  48,  footnote. 


Introduction.  5 

method,1  Parsons'  method,2  Cochran's  test,3  tne  Patrick  or  Iowa 
station  test,4  and  the  Beimling  (Leffmann  and  Beam)  test.8  Of 
foreign  methods  published  at  about  the  same  time,  or  previously, 
the  Lactocrite,6  Liebermann's  method,7  the  Schmid,8  Thorner,* 
Nahm,10  Bose-Gottlieb,11  sin-acid  method,12  and  the  Gerber  sal- 
method13  may  be  noted. 

8.  All  these  tests  were  similar  in  principle,  the  solids 
not  fat  of  the  milk  being  in  all  cases  dissolved  by  the 
action  of  one  or  more  chemicals,  and  the  fat  either 
measured  as  such  in  a  narrow  graduated  tube,  or 
brought  into  solution  with  ether,  gasoline,  etc.,  and  a 
portion  thereof  weighed  on  evaporation  of  the  solvent. 
While  this  principle  is  an  old  one,  having  been  em- 
ployed in  chemical  laboratories  for  generations,  its 
adaptation  to  practical  conditions,  and  the  details  as 
to  apparatus  and  chemicals  used  were,  of  course,  new 
and  different  in  each  case.  The  American  tests  given 
were  adopted  to  a  limited  extent  within  the  states  in 
which  they  originated  and  even  outside  of  them,  as  in 
the  case  of  the  Short,  Patrick  and  Beimling  methods. 
The  Babcock  test,  however,  soon  replaced  the  different 
methods  mentioned,  and  during  the  past  fifteen  years 

1  Kansas  experiment  station  report,  1888,  p.  149. 

2  N.  H.  experiment  station  report,  1888,  p.  69. 

3  Journal  of  Anal.  Ohem.,  Ill  (1889),  p.  381. 

*  la.  exp.  sta.,  bull.  No.  8,  Feb,  1890;  Iowa  Homestead,  June  14, 1889. 

5  Vermont  exp.  sta.,  bull.  No.  21,  September,  1890.     For  description 
of  these  and  other  volumetric  methods  of  milk  analysis,  see  Wiley,  Agri- 
cultural Analysis,  Vol.  Ill,  p.  490  et  seq ;  Wing,  Milk  and  its  Products,  p. 
33  et  seq,  and  Snyder,  Chemistry  of  Dairying,  pp.  112-113. 

6  Analyst,  1887,  p.  6. 

7  Fresenius1  Zeitschr.,  22,  383. 

8  Ibid.,  27,  464. 

9  Ohem.  Oentralbl.,  1892,  429. 

10  Milch-Zeitung,  1894,  No.  35;  1897,  No.  50. 

11  Landw.  Vers.  Stat.,  40,  1. 

12  Milch-Zeitung,  1904,  No.  27. 

13  Milch-Zeitung,  1906,  No.  8. 


6  Testing  Milk  and  Its  Products. 

or  more  it  has  been  in  almost  exclusive  use  in  creamer- 
ies and  cheese  factories  in  this  country,  where  payments 
are  made  on  the  basis  cf  the  quality  of  the  milk  deliv- 
ered, as  well  as  in  the  routine  work  in  experiment  sta- 
tion laboratories,  and  among  milk  inspectors  and  pri- 
vate dairymen. 

9.  The  Babcock  test.  The  main  cause  why  the 
Babcock  test  has  replaced  all  competitors  is  doubtless 
to  be  sought  in  its  simplicity  and  its  cheapness.  It  has 
but  few  manipulations,  is  easily  learned,  and  is  cheap, 
both  in  first  cost  and  as  regards  running  expenses. 

The  test  is  furthermore  speedy,  accurate,1  and  easily 
applied  under  practical  conditions,  and  may  therefore 
safely  be  considered  the  -best  milk  test  available  at  the 
present  time. 

The  method  is  applicable  not  only  to  whole  milk,  but 
to  cream,  skim  milk,  butter  milk,  whey,  condensed  milk, 
and  (if  a. small  scale  for  weighing  out  the  sample  is 
available,  to  cheese  and  butter.2 

With  all  its  advantages,  the  Babcock  milk  test  is  not 
in  every  respect  an  ideal  test.  The  handling  of  the 
very  corrosive  sulfuric  acid  requires  constant  care  and 
attention;  the  speed  of  the  tester,  the  strength  of  the 
acid,  the  temperature  of  the  milk  to  be  tested,  and  other 
points,  require  constant  watching,  lest  the  results  ob- 
tained be  too  low  or  otherwise  unsatisfactory.  In  the 
hands  of  careful  operators  the  test  can,  however,  al- 
ways be  relied  upon  to  give  most  satisfactory  results. 

1  For  u  summary  of  com  pa  rat  i\  «•  :ni;i  ]>><•>  m:i<l«-  l>v  tin-  HaU-cu-k  test 
and  uravinn-t  He  analysis  up  to  1892,  see  Hoard's  Dairyman,  Oct.  7,  1892, 
p.  -j.-rtW);  also  Schrott-Fiechtl,  Milrh/eltung,  1896,  p.  183  et  seq. 

2  Tin-  P.abcock  test,  like  the  ethrr-rxt  rartion  method  gives, 
somewhat  too  low  results  in  the  case  of  skim  milk  (l>7.) 


Introduction. 


10.  Foreign  methods.  In  European  countries  four 
practical  milk  and  cream  tests,  besides  the  Babcock  test, 
are  in  use  at  the  present  time,  viz.:  Gerber 's  acid- 
butyrometer,  the  lactocrite,De  Laval's  butyrometer,  and 
Fjord's  centrifugal  cream 
test.1 

Of  these  the  last  test 
given  has  never,  to  our 
knowledge,  been  intro- 
duced into  this  country, 
and  the  first  three  only 
on  a  small  scale. 

11.  The  Gerber  method2 

(fig.  1)  is  essentially  the  old 
Beimling  method  (7),  worked 
out  independently  by  the 
Swiss  chemist,  Dr.  N.  Gerber. 
In  this  test  sulfuric  acid  of 
the  same  strength  as  in  the 
Babcock  test  is  used,  and  a 
small  quantity  of  amyl  alco- 
hol is  added.  The  amyl  alcohol  facilitates  the  separation  of  the 
fat,  but  may  introduce  a  source  of  error  on  account  of  impuri- 
ties contained  therein,  when  the  results  obtained  with  a  new  lot  of 
alcohol  can  not  be  checked  against  gravimetric  analysis  or  against 
tests  made  with  amyl  alcohol  known  to  give  correct  results.  This 
method  is,  however,  extensively  used  in  European  countries,  hav- 
ing there  practically  replaced  the  Babcock  test  or  been  adopted 
in  preference  to  it. 

12.  The   Lactocrite  was    one   of    the    earliest    practical   milk 
tests  introduced.     It  was  invented  by   De  Laval  in   1886.     The 
acids  used  in  this  test  are  lactic  acid    (originally,   acetic   acid) 

1  The  Lister- Babcock  milk  test  advertised  in  English   papers  and 
known  as  such  in  England,  is  the  regular  Babcock  test,  to  which  the 
English  manufacturers  have  prefixed  their  name;  the  same  applies  to 
the  Ahlborn- Babcock  method  and  the  Krugmann- Babcock  method. 

2  Gerber,  Die  praktische  Milchpriifung,  7th  edition,  1900. 


Fig.  1.    The  Gerber  acid- 
butyrometer. 


8 


Testing  Milk  and  Its  Products. 


with  a  mixture  of  hydrochloric  and  sulfuric  acids.     This  test  is 
now  but  rarely  met  with. 

13.  In  the  De  Laval  butyrometer  (fig.  2)  the  same  acid  is 
used  as  in  the  Babcock  test,  but  the  tubes  employed  and  the 
manipulations  of  the  method  differ  materially  from  this  test;  a 
smaller  sample  of  milk  is  taken  (only  2  cc.)  and  a  correspond- 


FIG.  2.    De  Laval's  butyrometer. 

ingly  small  quantity  of  acid  used.  Where  a  large  number  of 
milk  samples  are  tested  every  day,  as  is  the  case,  for  instance, 
in  European  milk  control  stations,  the  butyrometer  may  be 
preferable  to  the  Babcock  test;  but  it  requires  more  skill  of  the 
operator  and  does  not  work  satisfactorily  in  case  of  sour,  lop- 
pered,  or  partially  churned  milk. 

14.  Fjord's  centrifugal  cream  tester1  (fig.  3)  is  exten- 
sively used  in  Denmark  and  is  mentioned  in  this  connection  as  it 
furnishes,  as  a  rule,  a  reliable  method  for  comparing  the  qual- 
ity of  different  lots  of  milk.  The  method  was  published  in  1878, 
by  the  late  N.  J.  Fjord,  director  of  the  state  experiment  station 
in  Copenhagen,  through  whose  exertions  and  on  whose  authority 
it  was  introduced  into  Danish  creameries  in  the  middle  of  the 

1  State  Danish  experiment  station,  Copenhagen,  sixth  and  ninth 
reports,  1885-7. 


Introduction. 


eighties.  No  chemicals  are  added  in  this  test,  the  milk  being 
simply  placed  in  glass  tubes,  seven  inches  long  and  about  two- 
thirds  of  an  inch  in  diameter,  and  whirled  for  twenty  minutes 
at  a  rate  of  2000  revolutions  per  minute  at  55°G  (131°F.). 
The  reading  of  the  cream  layer  thus  obtained  gives  the  per  cent, 
of  cream,  and  not  of  butter 
fat,  in  the  sample  tested.  One 
hundred  and  ninety-two  sam- 
ples of  milk  can  be  tested 
simultaneously.  Within  the 
limits  of  normal  Danish  herd 
milk,  the  results  obtained  cor- 
respond to  the  per  cents  of  fat 
present  in  the  samples,  one  per 
cent,  of  cream  being  equal  to 
about  0.7  per  cent,  of  fat; 
outside  of  these  limits  the  test 
is,  however,  unreliable,  especially  in  case  of  very  rich  milk  and 
strippers7  milk.  Only  sweet  milk  can  be  tested  by  this  method. 
Milk  tests  proper,  like  the  Gerber,  Babcock  and  De  Laval  tests, 
have  during  recent  years  been  introduced  into  Denmark,  and 
these  will  in  all  probability  in  time  force  the  Fjord  cream  test 
out  of  Danish  creameries,  for  similar  reasons  that  relegated  to 
obscurity  the  gravity  cream  tests.1 

1  Among  foreign  milk  te-ts  in  use  abroad  should  also  be  mentioned 
the  Lindstrom  butyrometer  and  the  Wollny  refractometer,  both  of  which, 
in  the  hands  of  trained  chemist*,  may  prove  better  adapted  for  use 
where  a  very  large  number  of  samples  are  to  be  tested  at  a  time,  than 
any  other  milk  test  available. 


FIG.  8.    Fjord's  centrifugal  cream 
tester. 


CHAPTER  I. 
COMPOSITION    OF   MILK   AND    ITS    PRODUCTS. 

Before  taking  up  the  discussion  of  the  Babccck  milk 
test,  a  brief  description  of  the  chemistry  of  milk  and  its 
products  is  given,  so  that  the  student  may  understand 
what  are  the  components  of  dairy  products,  and  the  re- 
lation of  these  to  each  other.  Only  such  points  as  have 
a  direct  bearing  upon  the  subject  of  milk  testing  and 
the  use  of  milk  tests  in  butter  and  cheese  factories  or 
private  dairies  will  be  treated  in  this  chapter,  and  the 
reader  is  referred  to  standard  works  on  dairying  for 
more  detailed  information  in  regard  to  the  composition 
of  dairy  products. 

15.  Composition  of  milk.  Milk  is  composed  of  the 
following  substances:  water,  fat,  casein,  albumen,  milk 
sugar,  and  ash.  A  few  other  substances  are  present  in 
small  quantities,  but  they  are  hardly  of  any  practical 
importance  and  will  not  be  considered  here.  The  com- 
ponents of  the  milk  less  the  water  are  known  collect- 
ively as  milk  solids  or  total  solids,  and  the  total  solids 
less  the  fat,  i.  e.,  casein,  albumen,  milk  sugar,  and  ash, 
are  often  spoken  of  as  solids  not  fat  or  the  non-fatty 
milk  solids.  The  milk  serum  includes  all  components 
of  the  milk  less  the  fat ;  the  serum  solids  are  therefore 
another  name  for  the  solids  not  fat;  when  given,  they 
are,  however,  generally  calculated  to  per  cent,  of  milk 
serum,  not  of  milk.  If,  e.  g.,  a  sample  of  milk  contains 


Composition  of  Milk  and  Its  Products.  11 

nine  per  cent,  of  solids  not  fat,  and  three  per  cent,  of 
fat,  the  milk  serum  will  make  up  97  per  cent,  of  the 
milk,  and  the  serum  solids,  9  x  10°  =  9.28  per  cent. 

97 
of  the  milk  serum. 

16.  Water.     The  amount  of  water  contained  in  cow's 
milk  ranges  from  82  to  90  per  cent.    Normal  cow's  milk 
will  not,  as  a  rule,  contain  more  than  88  per  cent,  of 
water,  nor  less  than  84  per  cent.    In  states  where  there 
are  laws  regulating  the  sale  of  milk,  as  is  the  case  in 
eighteen  states  of  the  Union  (see  Appendix,  Table  II), 
the  maximum  limit  for  water  in  milk  in  all  instances 
but  one  (South  Carolina)  is  88  per  cent. ;  the  state  men- 
tioned allows  88.5  per  cent,   of  water  in  milk  offered 
for  sale  within  her  borders.     The  effect  of  fraudulently 
increasing  the  water  content  of  milk  by  watering  is  con- 
sidered under  Adulteration  of  Milk   (121). 

17.  Fat.     The  fat  in  milk  is  net  in  solution,  but  sus- 
pended as  very  minute  globules,  which  form  an  emul- 
sion with  the  milk  serum;  the  globules  are  present  in 
immense  numbers,  viz.,  on  the  average  about  one  hun- 
dred millions  in  a  single  drop  of  milk ;  a  quart  of  milk 
will  contain  about  two  thousand  billions  of  fat  globules, 
a  number  written  with  thirteen  figures.     The  sizes  of 
the  globules  in  the  milk  from  the  same  cows  vary  ac- 
cording to  the  stage  of  the  period  of  lactation,  the  glob- 
ules being   largest   at   the   beginning   cf   the   lactation 
period,  and  gradually  decreasing  in  size  with  its  prog- 
ress.    Different   breeds   of   cows   have   fat   globules   of 
different   average   sizes ;   the   Channel    Island   cows   are 
thus  noted  for  the  relatively  large  fat  globules  of  their 


12  Testing  Milk  and  Its  Products. 

milk,  while  the  lowland  breeds,  the  Ayrshire,  and  other 
breeds  have  uniformly  smaller  globules.  The  diameter 
of  average  sized  fat  globules  in  fresh  milkers  is  about 
0.004  millimeter,  or  one  six-thousandth  of  an  inch ;  that 
is,  it  takes  about  six  thousand  such  globules  placed  side 
by  side  to  cover  one  inch  in  length.  The  globules  of 
any  I  sample  of  milk  vary  greatly  in  size;  the  largest 
globules  are  recovered  in  the  cream  when  the  milk  is 
set/or  run  through  a  cream  separator,  and  the  smallest 
ones  remain  in  the  skim  milk;  thoroughly  skimmed  sep- 
arator skim  milk  contains  only  a  small  number  of  very 
minute  fat  globules. 

Milk  fat  is  composed  of  so-called  glycerides  of  the 
fatty  acids,  i.  e.,  compounds  of  the  latter  with  glycerin ; 
some  of  the  fatty  acids  are  insoluble  in  water,  viz., 
palmitic,  stearic,  and  oleic  acids,  while  others  are  solu- 
ble and  volatile,  the  chief  ones  among  the  latter  being 
butyric,  caprylic,  and  capronic  acids.  The  glycerides 
of  the  insoluble  fatty  acids  make  up  about  92  per  cent, 
of  the  pure  milk  fat;  about  8  per  cent,  of  the  glycer- 
ides of  volatile  fatty  acids  are  therefore  found  in  nat- 
ural milk-  (and  butter-)  fat.  The  distinction  between 
natural  and  artificial  butter  lies  mainly  in  this  point, 
since  artificial  butter  (butterine,  oleomargarine)  as  well 
as  other  solid  animal  fats  contain  only  a  very  small 
quantity  of  volatile  fatty  acids.  The  glycerides  of  the 
volatile  fatty  acids  are  unstable  compounds,  and  are 
easily  decomposed  through  the  action  of  bacteria  or 
light ;  the  volatile  fatty  acids  thus  set  free,  principally 
butyric  acid,  are  the  cause  of  the  unpleasant  odor  nret 
with  in  rancid  butter. 


Composition  of  Milk  and  Its  Products.  13 

Cow's  milk  generally  contains  between  three  and  six 
per  cent,  of  fat;  in  American  milk  we  find,  on  the 
average,  toward  four  per  cent,  of  fat.  The  milk  from 
single  cows  in  perfect  health  will  occasionally  go  below 
or  above  the  limits  given,  but  mixed  herd  milk  rarely 
falls  outside  of  these  limits.  The  standard  adopted  by 
the  U.  S.  government  for  fat  in  milk  is  3.25  per  ct. 
The  legal  standard  for  fat  in  milk  in  most  states  of  the 
Union  is  3  per  cent. ;  Rhode  Island  allows  milk  contain- 
ing 2.5  per  cent,  of  fat  to  be  sold  as  pure,  while  Georgia 
and  Minnesota  require  it  to  contain  3.5  per  cent.,  and 
Massachusetts  3.7  per  cent,  (in  the  months  of  May  and 
June;  see  Appendix,  Table  II). 

18.  Casein  and  albumen.  These  belong  to  the  so- 
called  nitrogenous  substances,  distinguished  from  the 
other  components  of  the  mifk  by  the  fact  that  they  con- 
tain the  element  nitrogen.  Another  name  is  albumin- 
oids or  protein  compounds.  Casein  is  precipitated  by 
rennet  in  the  presence  of  soluble  calcium  salts,  and  by 
dilute  acids  and  certain  chemicals ;  albumen  is  not  acted 
upon  by  these  agents,  but  is  coagulated  by  heat,  a  tem- 
perature of  170°  F.  being  sufficient  to  effect  a  perfect 
coagulation.  The  casein,  fat,  and  water,  are  the  main 
components  of  nearly  all  kinds  of  cheese.  In  the  manu- 
facture of  cheddar  and  most  other  solid  cheeses,  the 
casein  is  coagulated  by  rennet,  and  the  curd  thus 
formed  holds  fat  and  whey  mechanically,  the  latter 
containing  in  solution  small  quantities  of  non-fatty 
milk  solids.  The  albumen  goes  into  the  whey  and  is 
lost  for  cheese  making;  in  some  countries  it  is  also  made 
into  cheese  by  evaporating  the  whey  under  constant 


14  Testing  Milk  and  Its  Products. 

stirring ;  whole  milk  of  cows  or  goats  is  often  added  and 
incorporated  into  such  cheese  (primosi,  gjetost). 

Casein  is  present  in  milk  partly  in  solution,  in  the 
same  way  as  milk  sugar,  soluble  ash-materials  and  albu- 
men, and  partly  in  suspension,  in  an  extremely  fine  col- 
loidal condition,  mixed  or  combined  with  insoluble  cal- 
cium phosphates.  The  casein  and  calcium  phosphates 
in  suspension  in  milk  may  be  retained  on  a  filter  made 
of  porous  clay  (so-called  Cliamberland  filters). 

About  80  per  cent,  of  the  nitrogenous  compounds  of 
normal  cow 's  milk  are  made  up  of  casein ;  the  rest  is 
largely  albumen.  If  the  amount  of  casein  in  milk  be 
determined  by  precipitation  with  rennet  *or  dilute  acids, 
and  the  albumen  by  boiling  the  filtrate  frcm  the  casein 
precipitate,  it  will  be  found  that  the  sum  of  these  two 
compounds  do  not  make  up  the  total  quantity  of  nitro- 
genous constituents  in  the  milk.  The  small  remaining 
portion  (about  five  per  cent,  of  the  total  nitrogenous 
constituents)  has  been  called  by  various  authors,  globu- 
lin, albumose,  hemi-albumose,  nuclein,  nucleon,  proteose, 
etc.  The  nitrogenous  constituents  of  milk  are  very  un- 
stable compounds,  and  their  study  presents  many  and 
great  difficulties ;  as  a  result  we  find  that  no  two  scien- 
tists who  have  made  a  special  study  of  these  compounds 
agree  as  to  their  properties,  aside  from  those  of  casein 
and  albumen,  or  their  relation  to  the  nitrogenous  sub- 
stances found  elsewhere  in  the  animal  body.  For  our 
pose  we  may,  however,  consider  the  nitrogen  com- 
pounds of  milk  as  made  up  of  casein  and  albumen,  and 
the  term  casein  and  albumen,  as  used  in  this  book,  is 
meant  to  include  the  total  nitrogenous  constituents  of 


Composition  of  Milk  and  Its  Products.  15 

milk,  obtained  by  multiplying  the  total  nitrogen  con- 
tent of  the  milk  by  6.25.1 

The  quantity  of  casein  in  normal  cow's  milk  will  vary 
from  2  to  4  per  cent.,  and  of  albumen,  from  .5  to  .8  per 
cent.  The  total  content  of  casein  and  albumen  ranges 
between  2.5  and  4.6  per  cent,  the  average  being  about 
3.2  per  cent.  Milk  with  a  low  fat  content  will  contain 
more  casein  and  albumen  than  fat,  while  the  reverse  is 
generally  true  in  case  of  milk  containing  more  than  3.5 
per  cent,  of  fat. 

19.  Milk  sugar  or  lactose  belongs  to  the  group  of 
organic  compounds  known  as  carbohydrates.  It  is  a 
commercial  product  manufactured  from  whey  and  is 
obtained  in  this  process  as  pale  white  crystals,  of  less 
sweet  taste  and  less  soluble  in  water  than  ordinary 
sugar  (cane  sugar,  sucrose).  About  70  per  cent,  of  the 
solids  in  the  whey,  and  33  per  cent,  of  the  milk  solids, 
are  composed  of  milk  sugar. 

When  milk  is  left  standing  for  some  time,  viz.,  from 
one  to  several  days,  according  to  the  temperature  of  the 
surrounding  medium  it  will,  as  a  rule,  turn  sour  and 
soon  become  thick  and  loppered.  This  change  in  the 
composition  and  appearance  of  the  milk  is  brought 
about  through  the  action  of  acid-forming  bacteria  on 
the  milk  sugar.  These  are  present  in  ordinary  milk  in 
immense  numbers,  and  under  favorable  conditions  of 
temperature  multiply  rapidly,  feeding  on  the  milk  sugar 

1  The  factor  6.25  is  generally  used  for  obtaining  the  casein  and  albu- 
men from  the  total  nitrogen  in  the  milk,  although  6.37  would  be  more 
correct,  since  these  substances,  according  to  our  best  authorities,  con- 
tain on  the  average  15.7  per  cent,  of  nitrogen  (  y1-^  =  6.8?) 


16  Testing  Milk  and  Its  Products. 

as  they  grow,  and  decomposing  it  into  lactic  acid.  When 
this  change  alone  occurs,  there  is  not  necessarily  a  loss 
in  the  nutritive  value  of  the  milk,  since  milk  sugar 
breaks  up  directly  into  lactic  acid,  as  shown  by  the  fol- 
lowing chemical  formula: 

C14H22011H20    (lactose)  =4  C3H003   (lactic  acid).1 

Ordinarily  the  souring  of  milk  is,  however,  more 
complicated,  and  other  organic  bodies,  like  butyric  acid, 
alcohol,  etc.,  and  gases  like  carbonic  acid  are  formed, 
resulting  in  a  less  in  the  feeding  value  of  the  milk. 
While  sour  milk  may  therefore  contain  a  somewhat 
smaller  proportion  of  food  elements  than  sweet  milk, 
it  will  generally  produce  better  results  when  fed  to 
farm  animals,  especially  pigs,  than  is  obtained  in  feed- 
ing similar  milk  in  a  sweet  condition.  The  cause  of  this 
may  lie  in  the  stimulating  effect  of  the  lactic  acid  of 
sour  milk  on  the  appetites  of  the  animals,  or  in  its  aid- 
ing digestion  by  increasing  the  acidity  of  the  stomach 
juices. 

That  the  souring  of  milk  is  due  to  the  activities  of 
bacteria  present  therein  is  shown  clearly  by  the  fact 
that  sterile  milk,  i.  e.,  milk  in  which  all  germ  life  has 
been  killed,  will  remain  sweet  for  any  length  of  time 
when  kept  free  from  infection. 

The  amount  of  milk  sugar  found  in  normal  cow's 
milk  varies  from  3.5  to  6  per  cent.,  the  average  content 
being  about  5  per  cent. ;  in  sour  milk  this  content  is 
decreased  to  toward  4  per  cent. 

1  One  molecule  of  mtlk  sugar  is  composed  of  12  atoms  of  carbon  (O)r 
±>  j i toms  of  hydrogen  (H).  11  atoms  ofoxyjrrn  <O>,  and  one  molecule  of 
water  (H2O).  In  the  s;iint'  way,  the  lactic-acid  molecule  consists  of  3 
atom-  of  carbon,  »}  atoms  of  hydrogen,  and  3  atoms  of  oxygen. 


Composition  of  Milk  and  Its  Products.  17 

20.  Ash.  The  ash  or  mineral  substances  of  milk  are 
largely  composed  of  chlorids  and  phosphates  of  sodium, 
potassium,  magnesium  and  calcium;  iron  oxid  and  sul- 
furic  and  other  acids  are  also  present  in  small  quanti- 
ties among  the  normal  mineral  milk  components.  The 
amounts  of  the  different  bases  and  acids  found  in  milk 
ash  have  been  determined  by  a  number  of  chemists ;  the 
average  figures  obtained  are  given  in  the  following 
table,  calculated  per  100  parts  of  milk  (containing  .75 
per  cent,  of  ash)  and  per  100  parts  of  milk  ash. 

Mineral  Components  of  Milk. 

In  per  cent,  of  Milk.    In  per  cent,  of  Ash. 

Potassium  oxid  (K2O) 19  per  ct.  25.64  per  ct. 

Sodium  oxid  (Na2O) 09  12.45 

Lime  (CaO) 18  24.58 

Magnesia  (MgO) 02  3.09 

Iron  oxid  (Fe2O3) 002  .34 

Phosphoric  anhydrid  (P2O5)...      .16  21.24 

Chlorin  (Cl) 12  16.34 

.762  per  ct.  103.68  per  ct. 

Less  oxygen,    corresponding  to 

chlorin  .  .  .012  3.68 


.75  100.00 

The  combinations  in  which  the  preceding  bases  and 
acids  are  contained  in  the  milk  are  not  known  with  cer- 
tainty. According  to  Soldner,  36  to  56  per  cent,  of  the 
phosphoric  acid  found  in  milk,  and  from  53  to  72  per 
cent,  of  the  lime,  are  present  in  suspension  in  the  milk 
as  di-  and  tri-calcium  phosphates,  and  may  be  filtered 
out  by  means  of  Chamberland  filters  (18),  or  by  long 
continued  centrifuging  (Babcock1).  The  rest  of  the 
ash  constituents  are  dissolved  in  the  milk  serum. 

1  Wis.  experiment  station,  twelfth  report,  p.  JKi. 
2 


18  Testing  Milk  and  Its  Products. 

The  ash  content  of  normal  cow's  milk  varies  but  lit- 
tle, as  a  rule  only  between  .6  and  .9  per  cent,  with  an 
average  of  .7  per  cent.  Milk  with  a  high  fat  content 
generally  contains  about  .8  per  cent,  of  ash;  strippers' 
milk  always  has  a  high  ash  content,  at  times  even  ex- 
ceeding one  per  cent.  Ordinarily,  the  mineral  constitu- 
ents are  least  liable  to  variations  of  any  of  the  com- 
ponents of  the  milk. 

21.  Other   components.     Besides  the  milk   constitu- 
ents enumerated  and  described  in  the  preceding  pages, 
normal  milk  contains  a  number  of  substances  which  are 
present  in  but  small  quantities  and  have  only  scientific 
interest,  such  as  the  milk  gases  (carbonic  acid,  oxygen, 
nitrogen),  citric  acid,  lecithin,  cholesterin,  urea,  hypo- 
xanthin,  lactochrome,  etc. 

22.  Average   composition.     The  average   percentage 
composition  of  cow's  milk  will  be  seen  from  Table  I  in 
the  Appendix.    The  following  statement  shows  the  lim- 
its within  which  the  components  of  normal  American 
cow's  milk  are  likely  to  come: 

Minimum.  Maximum.  Average. 

Water 82.0  per  ct.  90.0  per  ct.  87. 4  per  ct. 

Fat 2.3  7.8  3.7 

Casein  and  albumen 2.5  4.6  3.2 

Milk  sugar 3.5  6.0  5.0 

Ash 6  .9  .7 

23.  Colostrum    milk.      The   liquid   secreted    directly 
after  parturition  is  known  as  colostrum  milk  or  biest- 
ings.     It  is  a  thick,  yellowish,  viscous  liquid;  its  high 
content  of  albumen  and  ash  is  characteristic,  and  also 
its  low  content  of  milk  sugar.    Owing  to  the  large  quan- 


Composition  of  Milk  and  Its  Products.          19 

tity  of  albumen  which  colostrum  contains,  it  will  coagu- 
late on  being  heated  toward  the  boiling  point.  In  the 
course  of  four  or  five  days  the  secretion  of  the  udder 
gradually  changes  from  colostrum  to  normal  milk;  the 
milk  is  considered  fit  for  direct  consumption  or  for  the 
manufacture  of  cheese  and  butter,  when  it  does  not  co- 
agulate on  boiling  and  is  of  normal  appearance  as  re- 
gards color,  taste,  and  other  properties.  For  composi- 
tion of  colostrum  milk,  see  Appendix,  Table  I. 

24.  Composition  of  milk  products.  In  addition  to 
its  use  for  direct  consumption,  milk  is  the  raw-material 
from  which  cream,  butter,  cheese,  and  condensed  milk 
are  obtained. 

When  milk  is  left  standing  for  some  time  or  subjected 
to  centrifugal  force,  it  will  separate  into  two  distinct 
parts,  cream  and  skim  milk.  The  proportion  of  each 
part  which  is  obtained,  and  their  chemical  composition, 
will  depend  on  the  method  by  which  the  separation  is 
effected;  in  the  so-called  gravity  process  where  the 
cream  is  separated  on  standing— either  in  shallow  pans 
in  the  air,  or  in  deep  cans,  submerged  in  cold  water— a 
less  complete  separation  is  reached,  since  the  skim  milk 
obtained  is  richer  in  fat  than  when  the  separation  takes 
place  through  the  action  of  centrifugal  force. 

The  milk  is  now  always  in  modern  creameries  skimmed 
by  means  of  cream  separators.  Separator  cream  will 
contain  from  15  to  50  per  cent,  of  fat,  according  to  the 
adjustment  of  the  separator  and  of  the  milk  supply; 
ordinarily  it  contains  about  55  per  cent,  of  fat.  Cream 
of  average  quality,  in  addition  to  the  fat  content  given, 
consists  of  about  66  per  cent,  of  water,  3.8  per  cent. 


20  Testing  Milk  and  Its  Products. 

casein  and  albumen,  4.3  per  cent,  milk  sugar,  and  .5  per 
cent.  ash. 

The  skim  milk  is  made  up  of  the  milk  serum  (15)  and 
a  small  amount  of  fat,  viz.,  toward  .4  per  cent,  when 
obtained  by  the  gravity  process,  and  less  than  .2  per 
cent,  in  the  case  of  separator  skim  milk.  Milk  set  in 
shallow  pans  in  the  air,  or  in  deep  cans  in  water  above 
60°  F.,  will  give  skim  milk  containing  one-half  to  over 
one  per  cent,  of  fat.  Skim  milk  is  used  as  a  food  for 
young  farm  animals  or  as  human  food,  and  in  this 
country  only  in  exceptional  cases,  for  the  manufacture 
of  cheese. 

25.  Cream  is  used  for  the  manufacture  of  butter  or 
for  direct  consumption.  In  the  former  case  a  certain 
amount  of  acidity  is  generally  allowed  to  develop  there- 
in previous  to  the  churning  process.  This  secures  a 
more  complete  churning  and  produces  peculiar  flavors 
in  the  butter,  without  which  it  would  seem  insipid  to 
the  majority  of  people  in  this  country.  Nearly  all 
American  butter  is  salted  before  being  placed  on  the 
market.  Salt  is  a  preservative  and  for  a  limited  length 
of  time  prevents  butter  from  spoiling.  Unsalted  butter 
made  from  sweet  cream  is  a  common  food  article  in 
Southern  and  Middle  Europe,  but  only  an  insignificant 
amount  is  manufactured  and  consumed  in  America; 
salted  butter  made  in  Europe  also  contains  considerably 
less  salt  than  American  butter  (see  Appendix,  Table  I). 
Butter  contains  all  the  fat  of  the  cream  except  a  small 
portion  which  goes  into  the  butter  milk,  and  a  small 
unavci(l;il)l(k  mechanical  loss  incident  to  the  handling  of 
the  products.  Butter  should  contain  at  least  80  per 


Composition  of  Milk  and  Its  Products.          21 

cent,  of  fat  and  ordinarily  contains  about  83  per  cent. ; 
besides  this  amount  of  fat,  butter  is  generally  composed 
of  water,  about  13  per  cent.,  curd  and  milk  sugar  1  per 
cent.,  and  salt  3  per  cent. 

Butter  milk  has  a  composition  similar  to  skim  milk, 
but  varies  much  more  than  this  product,  according  to 
the  acidity,  temperature,  and  thickness  of  the  cream, 
and  other  churning  factors.  It  contains  about  9  per 
cent,  of  solids,  viz.,  milk  sugar  (and  lactic  acid)  4  per 
cent.,  casein  and  albumen  4  per  cent.,  fat  .3  per  cent., 
and  ash  .7  per  cent. 

26.  The  quantities  of  butter  and  by-products  obtained 
in  the  manufacture  of  butter  are  as  follows :    1000  Ibs. 
of  milk  of  average  quality  will  give  about  850  Ibs.  of 
skim  milk  and  145  Ibs.  of  cream   (separator  slime  and 
mechanical  loss,  5  Ibs.)  ;  this  amount  of  cream  will  make 
about  42  Ibs.  of  butter  and  100  Ibs.  of  butter  milk  (me- 
chanical loss,  3  Ibs.). 

27.  In  the  manufacture  of  American  cheddar  cheese, 
whole  milk  is  heated  to  about  86°  F.,  and  a  small  amount 
of  rennet  extract  is  added,  which  coagulates  the  casein ; 
the  albumen  of  the  milk  is  not  precipitated  by  rennet 
and  remains  in  solution  (18).   "  Green "  cheese,  as  taken 
from  the  press,  is  made  up,  roughly  speaking,  of  37  per 
cent,  of  water,  34  per  cent,  of  fat,  24  per  cent,  of  albu- 
minoids   (nearly  all  casein),  and  about  5  per  cent,  of 
milk  sugar,  lactic  acid,  and  ash  (largely  salt).     In  the 
curing  of  cheese  there  is  some  less  by  drying,  but  the 
main  changes  occur  in  the  breaking  up  of  the  firm  curd 
into  soluble  and  digestible  nitrogenous  compounds,  pep- 
tones, amids,  etc. 


22  Testing  Milk  and  Its  Products. 

Whey  is  the  by-product  obtained  in  the  manufacture 
of  cheese.  It  consists  of  water  and  less  than  7  per  cent, 
of  solids;  of  the  latter  about  5  per  cent,  is  milk  sugar, 
.8  per  cent,  albumen,  .6  per  cent,  ash,  and  .3  per  cent, 
fat.  Whey  is  generally  used  for  feeding  farm  animals ; 
it  is  the  raw-material  from  which  milk  sugar  and  whey 
cheese  are  made. 

28.  Condensed  milk  is  manufactured  from  whole  milk 
or  from  partially  skimmed  milk.  In  many  brands  a 
large  quantity  of  sugar  (25  per  cent,  or  more)  is  added 
to  the  condensed  milk  in  the  process  of  manufacture  so 
as  to  secure  perfect  keeping  quality  in  the  product. 
Brands  to  which  no  sugar  has  been  added  are  also  on 
the  market,  and  in  case  of  such  brands  the  relation  be- 
tween the  various  solid  constituents  of  the  condensed 
milk  will  be  essentially  the  same  as  that  between  the 
constituents  of  milk  solids.  Condensed  milk  should  con- 
tain at  least  9%  fat,  and  must  be  free  from  preserva- 
tives and  other  foreign  substances  (except  sugar). 

Tables  are  given  in  the  Appendix  showing  the  aver- 
age composition  of  the  various  milk  products. 

Questions. 

1.  What  is  the  average  composition  of  cow's  milk;  state  briefly 
the  properties  of  the  various  constituents. 

2.  What  is  meant  by  total  solids;  solids  not  fat;  milk  serum; 
serum  solids? 

3.  What  is  colostrum  milk?     Give  its  average  composition,  and 
in  what  particulars  it  mainly  differs  from  normal  milk. 

4.  Give  the  average   composition  of   cream,  skim  milk,  butter- 
milk, whey,  butter  and  cheddar  cheese. 

5.  Explain  the  distribution  of  the  components  of  milk  in    (a) 
butter-making,    (b)    cheese-making. 


CHAPTER  II. 
SAMPLING   MILK. 

29.  The  butter  fat  in  milk  is  not  in  solution,  like 
sugar  dissolved  in  water,  but  the  minute  fat  globules  or 
drops,  in  which  form  it  occurs,  are  held  in  suspension 
in  the  milk  serum  (17).  Being  lighter  than  the  serum, 
the  fat  globules  have  a  tendency  to  rise  to  the  surface 
of  the  milk.  If,  therefore,  a  sample  of  milk  is  left 
standing  for  even  a  short  time,  the  upper  layer  will 
contain  more  fat  than  the  lower  portion.  This  fact 
should  always  be  borne  in  mind  when  milk  is  sampled. 
The  rapidity  with  which  fat  rises  in  milk  can  be  easily 
demonstrated  by  allowing  a  quantity  of  sweet  milk  to 
stand  in  a  cylinder  or  a  milk  can  for  a  few  minutes, 
and  testing  separately  the  top,  middle  and  bottom  layer 
of  this  milk. 

The  amount  of  mixing  necessary  to  evenly  distribute 
the  constituents  of  milk  throughout  its  mass  may  be  as- 
certained by  adding  a  few  drops  of  cheese  color  to  a 
quart  of  milk.  The  yellow  streaks  through  the  milk 
will  be  noticed  until  it  has  been  poured  several  times 
from  one  vessel  to  another,  when  the  milk  will  have  a 
uniform  pale  yellow  color.  Stirring  with  a  stick  or  a 
dipper  will  not  produce  an  even  mixture  so  quickly  or 
so  completely  as  pouring  the  milk  a  few  times  from  o 
vessel  to  another ;  in  sampling  milk  for  testing  it  should 
always  be  mixed  by  pouring,  just  before  the  milk  is 
measured  into  the  bottle ;  if  several  tests  are  made  of  a 
sample,  the  milk  should  be  poured  before  each  sampling. 


24  Testing  Milk  and  Its  Products. 

• 
30.  Partially     churned     milk.     A   second    difficulty 

sometimes  met  with  in  sampling  whole  milk  arises  from 
the  fact  that  a  part  of  the  butter  fat  may  be  separated 
in  the  form  of  small  butter  granules,  by  too  zealous  mix- 
ing or  by  reckless  shaking  in  preparing  the  sample  for 
testing.  This  will  happen  most  readily  in  case  of  milk 
from  fresh  cows  or  milk  containing  exceptionally  large 
fat  globules.  When  some  of  the  butter  granules  are 
thus  churned  out,  they  quickly  rise  to  the  surface  of 
the  milk  after  pouring  and  cannot  again  be  incorporated 
in  the  milk  by  simple  mixing;  it  is,  therefore  impossi- 
ble to  obtain  a  fair  sample  of  such  milk  for  testing 
without  taking  special  precautions  which  will  be  ex- 
plained in  the  following.  The  granules  of  butter  may 
be  so  small  as  to  pass  into  the  pipette  with  the  milk  and 
the  quantity  measured  thus  contain  a  fair  proportion 
of  them,  but  they  will  be  found  sticking  to  the  inside 
of  the  pipette  when  this  is  emptied,  and  thus  fail  to  be 
carried  into  the  test  bottle  with  the  milk. 

A  similar  partial  churning  of  the  milk  will  sometimes 
take  place  in  the  transportation  cans.  "When  such  milk 
is  received  at  the  factory,  the  butter  granules  are  caught 
by  the  strainer  cloth  through  which  the  milk  is  poured, 
and  are  thus  lost  both  to  the  factory  and  to  the  farmer. 
This  separated  fat  cannot  be  added  to  the  cream  or  to 
the  granular  butter,  without  running  the  risk  of  mak- 
ing mottled  butter,  and  it  will  not  enter  into  the  sam- 
ple of  milk  taken  for  testing  purposes. 

When  milk  samples  are  sent  by  mail  or  express  in 
small  bottles,  or  carried  to  the  place  of  testing,  they 
often  arrive  with  lumps  rf  Imllor  floating  in  the  milk 


Sampling  Milk.  25 

or  sticking  to  the  glass.  This  churning  of  the  milk  can 
be  easily  prevented  by  completely  filling  the  bottle  or 
the  can.  If  there  is  no  space  left  for  the  milk  in  which  to 
splash  around,  the  fat  will  not  be  churned  out  in  transit. 

31.  Approximately  accurate  results  may  generally  be 
obtained  with  a  partially  churned  sample  of  milk,  if  a 
teaspoonful  of  ether  be  added  to  it.  After  adding  the 
ether,  cork  the  bottle  and  shake  it  until  the  lumps  of 
butter  are  dissolved.  This  ether  solution  of  the  butter 
will  mix  with  the  milk  and  from  the  mixture  a  fairly 
satisfactory  sample  may  generally  be  taken.  The  dilu- 
tion of  milk  by  the  ether  introduces  an  error  in  the 
testing,  and  only  the  smallest  quantity  of  ether  neces- 
sary to  dissolve  the  lumps  of  butter  should  be  used.  If 
desired,  a  definite  quantity  of  ether,  say  five  per  cent, 
of  the  volume  of  the  sample  of  milk  to  be  tested,  may 
be  added ;  in  such  cases  the  result  of  the  test  must  be 
increased  by  the  per  cent,  of  ether  added. 

EXAMPLE. — To  a  4-oz.  sample  (120  cc.)  of  partially  churned 
milk,  5  per  cent,  or  6  cc.,  of  common  ether  are  added;  the  mix- 
ture gave  an  average  test  of  4  2  per  cent.  The  test  must  be  in- 
creased by  Yg0X4.2=.21,  and  the  original  milk  therefore  con- 
tained 4.2+.21=4.41  per  cent,  of  fat. 

Milk  containing  ether  must  be  mixed  cautiously  with 
acid  in  making  a  test,  so  as  to  avoid  loss  of  the  contents 
of  the  bottle  by  the  sudden  boiling  of  the  ether  due  to 
the  heat  evolved  in  mixing  the  milk  and  the  acid. 

Instead  of  adding  ether  to  partially  churned  sam- 
ples, the  milk  may  be  heated  to  about  110°  F.  for  a 
few  minutes,  so  as  to  melt  the  butter  granules;  the 
sample  is  now  shaken  vigorously  until  a  uniform  mix- 
ture of  milk  and  melted  butter  is  obtained,  and  a  pi- 
petteful  then  quickly  drawn  from  the  sample. 


26  Testing  Milk  and  Its  Products. 

32.  Sampling  sour  milk.  When  milk  becomes  sour, 
the  casein  is  coagulated  and  the  mechanical  condition  of 
the  milk  thereby  changed  so  as  to  render  difficult  a  cor- 
rect sampling.  The  butter  fat  is  not,  however,  changed 
in  the  process  of  souring;  this  has  been  shown  by  one 
of  us,  among  others,  in  a  series  of  tests  which  were 
measured  from  one  sample  of  sweet  milk  into  six  test 
bottles.  A  test  of  the  milk  in  one  of  these  test  bottles 
was  made  every  month  for  six  months,  and  approxi- 
mately the  same  amount  of  fat  was  obtained  in  the 
tests  throughout  the  series,  as  was  found  originally  in 
the  milk  when  tested  in  a  sweet  condition.1  If  the  milk 
is  in  condition  to  be  sampled,  its  souring  does  not  there- 
fore interfere  with  its  being  tested  by  the  Babcock  test 
or  with  the  accuracy  of  the  results  obtained. 

In  order  to  facilitate  the  sampling  of  sour  or  lop- 
/  pered  milk,  some  chemical  may  be  added  which  will  re- 
dissolve  the  coagulated  casein  and  produce  a  uniform 
mixture  that  can  be  readily  measured  with  a  pipette. 
Any  alkali  (powdered  potash  or  soda,  or  liquid  ammo- 
nia) will  produce  this  effect.  Only  a  very  small  quan- 
tity of  powdered  alkali  is  necessary  for  this  purpose. 
The  complete  action  of  the  alkali  on  sour  milk  requires 
a  little  time,  and  the  operator  should  not  try  to  hasten 
the  solution  by  adding  too  much  alkali.  An  excess  of 
alkali  will  often  cause  such  a  violent  action  of  the  sul- 
furic  acid  on  the  milk  to  which  the  acid  is  added  (on 
account  of  the  heat  generated  or  the  presence  of  car- 
bonates in  the  alkali)  that  the  mixture  will  be  thrown 

l  See  Hoard's  Dairyman,  April  8,  1892.  The  same  holds  true  for 
cream,  as  shown  by  Winton  (U.  S.  Dept.  Agr.,  Div.  of  Chemistry,  bull. 
48,  p.  112). 


Testing  Milk  and  Its  Products.  27 

out  of  the  neck  of  the  test  bottle  when  this  is  shaken  in 
mixing  the  milk  and  the  acid  (37).  When  powdered 
alkali  is  added  to  the  milk,  it  should  be  allowed  to 
stand  for  a  while,  with  frequent  shaking,  until  the  curd 
is  all  dissolved  and  an  even  translucent  liquid  is  ob- 
tained. Such  milk  may  become  dark-colored  by  the  ac- 
tion of  the  alkali,  but  this  color  does  not  interfere  with 
the  accuracy  of  the  test. 

Instead  of  powdered  soda  or  potash,  these  substances 
dissolved  in  water  (soda  or  potash  lye),  or  strong  am- 
monia, may  be  used  for  the  purpose  of  dissolving  the 
coagulated  casein  in  sour  milk.  In  this  case,  a  definite 
proportion  of  alkali  solution  must  be  taken,  however,  5 
per  cent,  of  the  volume  of  milk  being  usually  sufficient, 
and  the  results  obtained  are  increased  accordingly. 

33.  Sampling  frozen  milk.  When  milk  freezes,  it 
separates  into  two  distinct  portions :  Milk  crystals, 
largely  made  up  of  water,  with  a  small  admixture  of  fat 
and  other  solids,  and  a  liquid  portion,  containing  nearly 
all  the  solids  of  the  milk.  In  sampling  frozen  milk  it 
is  therefore  essential  that  the  liquid  and  the  frozen  part 
be  warmed  and  thoroughly  mixed  by  pouring  gently 
back  and  forth  from  one  vessel  into  another;  the  sam- 
ple is  then  taken  and  the  test  proceeded  with  in  the 
ordinary  manner  (36). 

Questions. 

1.  What   precautions  must  be  taken   in   sampling  milk?     Give 
reasons. 

2.  How  can  a  fair  sample  be  taken  of   (a)    partially  churned 
milk,   (b)  sour  milk,   (c)  frozen  milk? 

3.  If  15  cc.  of  ammonia  are  added  to   500  cc.  of  sour  milk, 
and  a  test  of  3.45  obtained,  what  is  the  correct  test  of  the  milk? 


CHAPTER  III. 


THE  BABCOCK  TEST. 

34.  The  Babcock  test  is  based  on  the  fact  that  strong 
sulfuric  acid  will  dissolve  all  non-fatty  solid  constitu- 
ents of  milk  and 
other  dairy  products, 
and  thus  enable  the 
fat  to  separate  on 
standing.  To  effect  a 
speedy  and  complete 
separation  of  the  fat, 
the  bottles  holding 
the  mixture  of  milk 
and  acid  are  placed 
in  a  centrifugal  ma- 
chine,  a  so-called 
tester,  and  whirled 
for  four  minutes ;  hot 
water  is  then  added 
so  as  to  bring  the 
liquid  fat  into  the 
graduated  neck  of 
the  test  bottles,  and 
after  a  repeated 
whirling,  the  length 
of  the  column  of  fat  is  read  off,  showing  the  per  cent, 
of  fat  contained  in  the  sample  tested. 


FIG.  4.    The  first  Babcock  tester  made. 


The  Babcock  Test.  29 

Sulfuric  acid  is  preferable  to  other  mineral  acids  for 
the  purpose  mentioned,  on  account  of  its  affinity  to 
water ;  when  mixed  with  milk,  the  mixture  heats  greatly, 
thus  keeping  the  fat  liquid  without  the  application  of 
artificial  heat  and  rendering  possible  a  distinct  reading 
of  the  column  of  fat  brought  into  the  neck  of  the  test 
bottles. 

So  far  as  is  known,  any  kind  of  milk  can  be  tested 
by  the  Babccck  test.  Breed,  period  of  lactation,  qual- 
ity or  age  of  the  milk  is  of  no  importance  in  using  this 
method,  so  long  as  a  fair  sample  of  milk  can  be  secured. 
In  cases  of  samples  of  milk  or  other  dairy  products 
rich  in  solids  it  requires  a  little  more  effort  to  obtain  a 
thorough  mixture  with  the  acid  than  with  dairy  prod- 
ucts low  in  solids,  like  skim  milk  or  whey,  which  may 
be  readily  mixed  with  the  acid. 

A.— DIRECTIONS  FOR  MAKING  THE  TEST. 

35.  The   various  steps   in  the    manipulation   of    the 
Babcock  test  are  discussed  in  the  following  pages;  at- 
tention is  drawn  to  the  difficulties  which  the  beginner 
and  others  may  encounter  in  the  use  of  the  test,  and 
the  necessary  precautions  to  be   observed  in  order  to 
obtain  accurate  and  satisfactory  results  are  explained 
in  detail.     The  effort  has  been  to  treat  the  subject  ex- 
haustively and  from  a  practical  point  of  view,  so  that 
persons  as  yet  unfamiliar  with  the  test  may  turn   to 
the  pages  of  this  book  for  help  in  any  difficulties  which 
they  may  meet  in  their  work  in  this  line. 

36.  Sampling.    The  sample  to  be  tested  is  first  mixed 
by  pouring  the  milk  from  one  vessel  to  another  two  or 


30 


Testing^.  M'ilk  and  Its  Products. 


three  times,  so  that  every  portion  thereof  will 
contain  a  uniform  amount  of  butter  fat  (29). 
The  measuring  pipette  (fig.  6),  which  has  a 
capacity  of  17.6  cubic  centimeters,1  is  filled  with 
the  milk  immediately  after  the 
mixing  i§  completed,  by  suck- 
ing the  milk  into  it  until  this 
rises  a  little  above  the  mark 
around  the  stem  of  the  pipette; 
the  forefinger  is  then  quickly 
placed  over  the  end  of  the  pi- 
pjette  before  the  milk  runs  down 
below  the  mark.  By  slightly 
releasing  the  pressure  of  the 
finger  on  the  end  of  the  pipette, 
the  milk  is  now  allowed  to  run 
down  until  it  just  reaches  the 
mark  on  the  stem ;  the  quantity 
of  milk  contained  in  the  pi- 
pette will  then,  if  this  is  cor- 
rectly made,  be  exactly  17.6  cc. 
The  finger  should  be  dry  in 
measuring  out  the  milk  so  that 
the  delivery  of  milk  may  be 
readily  checked  by  gentle  pres- 
sure on  the  upper  end  of  the 
It  1  ill  pipette. 

The   point   of  the   pipette   is 
now   placed   in   the   neck   of   a 
test    bottle     (fig.    5), 


FIG.  5.  Bibcock  milk,-.    ,  , 

testbottio.        n.'incock 


n 


pette. 


1  See  p.  45,  foot  note. 


"^x 

JV0 

The  ^a^coc^^L/BRA^ 

and  the  milk  is  allowed  to  flow  slowly  down  the  inside 
of  the  neck.  Care  must  be  taken  that  none  of  the  milk 
measured  out  is  lost  in  this  transfer.  The  portion  of 
the  milk  remaining  in  the  point  of  the  pipette  is  blown 
into  the  test  bottle. 
The  best  and  saf- 
est manner  of  hold- 
ing the  bottle  and  the 
pipette  in  this  trans- 
fer is  shown  in  fig. 
7.  Fig.  8  shows  a 
position  which  should 
be  avoided,  since  by 
holding  the  bottle  in 

this    way,     there     is     P         danger  that  some  of  the 

milk  may  completely  fill 
the  neck  of  the  bottle, 
and  as  a  result,  flow 
over  the  top  of  the  neck. 
Pipettes,  the  lower 
part  of  which  slip  read- 
ily into  the  necks  of  the 
test  bottles,  may  be 
emptied  by  lowering 
the  pipette  into  the 
neck  of  the  bottle  till 
it  rests  on  its  rim,  when 
the  milk  is  allowed  to 

FIG.  7.    The  right  way  of  emptying 

pipette  into  test  bottle.  run  into  the  test  bottle.  , 

37.  Adding   acid.     The   acid  cylinder    (fig.   9)    hold- 
ing 17.5  cc.,  is  filled  to  the  mark  with  sulfuric  acid  of 


32 


Testing  Milk  and  Its  Products. 


a  specific  gravity  of  1.82-1.83.  This  amount  of  acid  is 
carefully  poured  into  the  test  bottle  containing  the  milk. 
In  adding  the  acid,  the  test  bottle  is  conveniently  held 
at  an  angle  (see  fig.  7),  so  that  the  acid  will  run  down 
the  wall  of  the  bottle  and 
not  run  in  a  small  stream  into 
the  center  of  the  milk,  the 
bottle  being  slowly  turned 
around  and  the  neck  thus 
cleared  of  adhering  milk.  By 
pouring  the  acid  into  the 
middle  of  the  test  bottle, 
there  is  also  a  danger  of  com- 
pletely filling  this  with  acid, 
in  which  case  the  plug  of 
acid  formed  will  be  pushed 
over  the  edge  of  the  neck  by 
the  expansion  of  the  air  in 
the  bottle,  and  may  be  spilled 
on  the  hands  of  the  operator. 
The  milk  and  the  acid  in 
the  test  bottle  should  be  in 
two  distinct  layers,  without 
much  of  a  black 
band  of  partially 
mixed  liquids  be- : 
tween  them.  Such 

a  dark  layer  is  of-  into  trst  hotti. . 

ten  followed  by  an  indistinct  separation  of  the  fat  in 
the  final  reading.  The  cause  of  this  may  be  that  a  par- 
tial mixture  of  acid  and  milk  before  the  acid  is  diluted 


FIG.  8.    The  wrong  way  of  emptying  pipette 


The  Babcock  Test.  33 

with  the  water  of  the  milk  may  bring  about  too  strong 
an  action  of  the  acid  on  this  small  portion  of  the  milk, 
and  thus  char  the  fat  contained  therein.  The  appear- 
ance of  black  flocculent  matter  in  or  below  the  col- 
umn of  fat  which  generally  results,  in 
either  case  renders  a  correct  measurement' 
difficult  and  at  times  even  impossible;  if 
the  black  specks  occur  in  the  fat  column 
itself,  the  readings  are  apt  to  be  too  high; 
if  below  it,  the  difficulty  comes  in  decid- 
ing where  the  column  of  fat  begins. 

38.  Mixing  milk  and  acid.  After  add- 
ing the  acid,  this  is  carefully  mixed  with: 
the  milk  by  giving  the  test  bottle  a  rotary 
motion.  In  doing  this,  care  should  be 
acid  cyiinde?.'  taken  that  the  liquid  is  not  shaken  into 
the  neck  of  the  test  bottle.  When  once  begun,  the  mix- 
ing should  be  continued  until  completed ;  a  partial  and 
interrupted  mixing  of  the  liquids  will  often  cause  more 
or  less  black  material  to  separate  with  the  fat  when  the 
test  is  finished.  Clots  of  curd  which  separate  at  first 
by  the  action  of  the  acid  on  the  milk,  must  be  entirely 
dissolved  by  continued  and  careful  shaking  of  the  bot- 
tle. Beginners  sometimes  fail  to  mix  thoroughly  the 
milk  and  the  acid  in  the  test  bottle.  As  the  acid  is 
much  heavier  than  the  milk  a  thin  layer  of  it  is  apt  to 
be  left  unnoticed  at  the  bottom  of  the  bottle,  unless  this 
is  vigorously  shaken  toward  the  end  of  the  operation. 

The  mixture  becomes  hot  by  the  action  of  the  acid'  on 
the  water  in  the  milk  and  turns  dark  colored,  owing 'to 
the  effect  of  the  strong  sulfuric  acid  on  the  nitrogenous 
constituents  and  the  sugar  in  the  milk. 

3 


34  Testing  Milk  and  Its  Products. 

Colostrum  milk  or  milk  from  fresh  cows  will  form  a 
violet  colored  mixture  with  the  acid,  due  to  the  action 
of  the  latter  on  the  albumen  present  in  such  milk  in 
considerable  quantities  (23). 

When  milk  samples  are  preserved  by  means  of  potas- 
ium  bichromate  (190),  and  so  much  of  this  material  has 
been  added  that  the  milk  has  a  dark  yellow  or  reddish 
color,  the  mixture  of  milk  and  acid  will  turn  greenish 
black,  and  a  complete  solution  is  rendered  extremely 
difficult  on  account  of  the  toughening  effect  of  the, bi- 
chromate on  the  precipitated  casein.  The  difficulty  is 
still  more  pronounced  with  milk  preserved  with  for- 
maldehyd. 

39.  Whirling  bottles.  After  the  milk  and  the  acid 
have  been  completely  mixed,  the  test  bottle  is  at  once 
placed  in  the  centrifugal  machine  or  tester  and  whirled 
for  four  or  five  minutes  at  a  speed  of  600  to  1200  revo- 
lutions per  minute,  according  to  the  diameter  of  the 
tester  (66).  It  is  not  absolutely  necessary  to  whirl  the 
test  bottles  in  the  centrifuge  as  soon  as  the  milk  and 
the  acid  are  mixed,  although  this  method  of  procedure 
is  much  to  be  preferred ;  they  may  be  left  in  this  condi- 
tion for  any  reasonable  length  of  time  (24  hours,  if 
necessary)  without  the  test  being  spoiled.  If  left  until 
the  mixture 'becomes  cold,  the  bottles  should,  however, 
be  placed  in  warm  water  (of  about  160°  F.)  for  about 
15  minutes  before  whirling. 

Four  minutes  at  full  speed  is  sufficient  for  the  first 
whirling  of  the  test  bottles  in  the  centrifuge;  this  will 
brin£  all  fat  to  the  surface  of  the  liquid  in  the  bottle. 


The  Babcock  Test. 


35 


—      7 


4O.  Adding  water.  Hot  water  is  now  added  by  means 
of  a  pipette  or  some  special  device  (10  in  fig.  58),  until 
the  bottles  are  filled  to  near  the  scale  on  the  neck  (80). 
The  bottles  are  whirled  again  at  full  speed  for  one  min- 
ute, and  hot  water  added  a  second  time,  until  the  lower 
part  of  the  column  of  fat  comes  within  the  scale  on  the 
neck  of  the  test  bottle,  preferably  to  the  1  or  2  per 
cent,  mark,  so  as  to  allow  for  the  sinking  of  the  column 
of  fat,  due  to  the  gradual  cooling  of  the  contents  of  the 
bottle.  By  dropping  the  water  directly  on  the  fat  in 
the  second  filling,  the  column  of  fat  will  be  washed  free 
from  light  flocculent  matter,  which  might  otherwise  be 
entangled  therein  and  render  the 
reading  uncertain  or  too  high.  A 
final  whirling  for  one  or  two  min- 
utes completes  the  separation  of 
_j  the  fat. 

41.  Measuring  the  fat.  The 
amount  of  fat  in  the  neck  of  the 
bottle  is  measured  by  the  scale  or 
graduations  on  the  neck.  Each 
division  of  the  scale  represents 
two-tenths  of  one  per  cent,  of  fat, 
and  the  space  filled  by  the  fat 
shows  the  per  cent,  of  butter  fat 
contained  in  the  sample  tested. 
FIG.  10.  Measuring  the  The  fat  *  measured  from  the 
B0abcno?kt0efstf^ttre.a  lower  line  of  separation  between 
the  fat  and  the  water,  to  the  top  of  the  fat  column,  at 
the  point  &,  shown  in  the  figure,  the  reading  being  thus 
taken  from  a  to  h,  and  not  to  c  or  to  d.  Comparative 


36  Testing  milk  and  its  Products. 

gravimetric  analyses  have  shown  that  the  readings  ob- 
tained in  this  manner  gi^  correct  results.  While  the 
lower  line  of  the  fat  column  is  nearly  straight,  the  upper 
one  is  curved,  and  errors  in  the  reading  are  therefore 
easily  made,  unless  the  preceding  rule  is  observed. 

The  fat  obtained  should  form  a  clear  yellowish  liquid 
distinctly  separated  from  the  acid  solution  beneath  it. 
There  should  be  no  black  or  white  sediment  in  or  below 
the  column  of  fat,  and  no  bubbles  or  foam  on  its  sur- 
face. The  bottles  must  be  kept  warm  until  the  read- 
ings are  made,  so  that  the  column  of  fat  will  have  a 
sharply  defined  upper  and  lower  meniscus.  When  the 
testing  is  done  in  a  cold  room,  it  is  a  good  plan  to  place 
the  bottles  in  a  pail  with  water  of  140°  F.  be- 
fore readings  are  made.  The  readings  should  always 
be  made  when  the  fat  has  a  temperature  of  about  140° 
F. ;  too  low  results  will  be  obtained  if  the  fat  is  allowed 
to  cool  below  120°  F.,  and  too  high  if  readings  are 
taken  above  150°.  The  fat  separated  in  the  Babcock 
test  solidifies  at  about  100°  F.  If  the  fat  is  partly  sol- 
idified, it  is  impossible  to  make  an  accurate  reading.1 

42.  Readings  of  tests  of  milk  made  in  steam  turbine 
testers  with  tightly  closed  covers  which  prevent  the  free 
escape  of  exhaust  steam  (71) ,  will  come  .2  to  .3  per  cent. 

x  The  effect  of  differences  in  the  temperature  of  the  fat  on  the  read- 
ings obtained  will  be  seen  from  the  following:  If  110  and  150°  F.  be 
taken  as  the  extreme  temperatures  at  which  readings  can  be  made, 
this  difference  of  40°  F.  (22.8°  O.)  would  HIM  UP  a  difference  in  the  volume 
of  the  fat  column  obtained  in  case  of  10  per  cent,  milk,  of  .00064  x  2  x  22.3 
=  .028544  cc.,  or  .14  per  cent.,  .00064  being  the  expansion  coefficient  of  pure 
butter  fat  per  degree  Centigrade  between  50  and  100°  O.  fZune,  Anal y si- 
des Beurre*,  I,  87),  and  2,  the  volume  of  the  fat  in  cc.  contained  In  17.6  cc. 
of  10  per  cent.  milk.  On  5  per  cent  milk  this  «-xtn»me  difference  would 
therefore  be  about  .07,  or  nearly  one-tenth,  of  one  per  cent. 


The  Babcock  Test.  37 

too  high  if  the  temperature  of  the  fat  is  allowed  to  rise 
to  that  of  the  exhaust  steam^during  the  process  of  whirl- 
ing. In  such  cases  the  test  bottles  must  be  allowed  to 
cool  to  about  140°,  by  placing  them  in  water  of  this 
temperature  for  a  few  minutes,  before  readings  are 
taken.1 

A  pair  of  dividers  will  be  found  convenient  for  meas- 
uring the  fat,  and  the  liability  of  error  in  reading  is 
decreased  by  their  use.  The  points  of  the  dividers  are 
placed  at  the  upper  and  lower  limits  of  the  fat  column 
(from  a  to  6  in  fig.  10).  The  dividers  are  now  lowered, 
one  point  being  placed  at  the  zero  mark  of  the  scale, 
and  the  mark  at  which  the  other  point  touches  the  scale 
will  show  the  per  cent,  of  fat  in  the  sample  tested.. 
The  dividers  must  be  tight  in  the  joint  to  be  of  use  for 
this  purpose. 

B. — DISCUSSION  OF  THE  DETAILS  OF  THE 
BABCOCK   TEST. 

43.  The  main  points  to  be  observed  as  to  apparatus 
and  testing  materials  in  order  to  obtain  correct   and 
satisfactory  results  by  this  test  will  now  be  considered, 
and  such  suggestions   and  help   offered  as   have   been 
found  needful  from  past  experience  with  a  great  variety 
of  samples  of  milk,   apparatus,  and  accessories.    * 

1.  — GLASSWARE. 

44.  Test  bottles.     The  test  bottles  should  have  a  ca- 
pacity of  about  50  cc.,  or  less  than  two  ounces;  they 
should  be  made  of  well-annealed  glass  that  will  stand 

1  See  Wis.  experiment  station  rep.  XVII,  p.  76. 


38  Testing  Milk  and  Its  Products. 

sudden  changes  of  temperature  without  breaking,  and 
should  be  sufficiently  heavy  to  withstand  the  maximum 
centrifugal  force  to  which  they  are  likely  to  be  sub- 
jected in  making  tests.  This  force  may,  on  the  average, 
be  not  far  from  30.65  Ibs.  (see  66),  which  is  the  pres- 
sure exerted  in  whirling  the  bottles  filled  with  milk  and 
acid  in  a  centrifugal  machine  of  18  inches  diameter  at 
a  speed  of  800  revolutions  per  minute. 

Special  forms  of  test  bottles  used  in  testing  cream 
and  skim  milk  are  described  under  the  heads  of  cream 
and  skim-milk  testing  (89,  90,  91,  99). 

When  17.6  cc.,  or  18  grams  of  milk  (48),  are  meas- 
ured into  the  Babcock  test  bottle,  the  scale  on  the  neck 
of  the  bottles  will  show  directly  the  per  cent,  of  fat 
found  in  the  milk.  The  scale  is  graduated  from  0  to 
10  per  cent.  10  per  cent,  of  18  grams  is  1.8  grams.  As 
the  specific  gravity  of  pure  butter  fat  (i.  e.,  its  weight 
compared  with  that  of  an  equal  volume  of  pure  water) 
at  the  temperature  at  which  the  readings  are  made 
(about  140°  P.),  is  0.9,  then  1.8  grams  of  fat  will  oc- 
cupy a  volume  of  J^-=2  cubic  centimeters.  The  space 
between  the  0  and  10  per  cent,  marks  on  the  necks  of 
the  test  bottles  must  therefore  hold  exactly  2  cubic  cen- 
timeters. The  scale  is  divided  into  10  equal  parts,  each 
part  representing  one  per  cent.,  and  each  of  these  is 
again  sub-divided  into  five  equal  parts.  Each  one  of  the 
latter  divisions  therefore  represents  two-tenths  of  one  per 
cent,  of  fat  when  17.6  cc.  of  milk  is  measured  out.  The 
small  divisions  are  sufficiently  far  apart  in  most  Bab- 
cock  test  bottles  to  make  possible  the  estimation  of  one- 
tenth,  or  even  five-hundredths,  of  one  per  cent,  of  fat 
in  the  samples  tested. 


The  Babcock  Test.  39 

As  the  necks  of  Babcock  test  bottles  vary  in  diame- 
ter, each  separate  bottle  must  be  calibrated  by  the  manu- 
facturers ;  the  length  of  the  scale  is  not,  for  the  reasons 
given,  apt  to  be  the  same  in  different  bottles.1 

If  the  figures  and  lines  of  the  scale  become  indistinct 
by  use,  the  black  color  may  be  restored  by  rubbing  a 
soft  pencil  over  the  scale,  or  by  the  use  of  a  piece  of 
burnt  cork  after  the  scale  has  been  rubbed  with  a  little 
tallow.  On  wiping  the  neck  with  a  cloth  or  a  piece  of 
paper  the  black  color  will  show  in  the  etchings  of  the 
glass,  making  these  plainly  visible. 

45.  Marking  test  bottles.  Test  bottles  can  now  be 
bought  with  a  small  band  or  portion  of  their  neck  or 
body  ground  or  "frosted,"  for  numbering  the  bottles 
with  a  lead  pencil.  Bottles  without  this  ground  label 
can  be  roughened  at  any  convenient  spot  by  using  a  wet 
fine  file  to  roughen  the  smooth  surface  of  the  glass. 
There  is  this  objection  to  the  latter  method  that  unless 
carefully  done,  it  is  apt  to  weaken  the  bottles  so  that 
they  will  easily  break,  and  to  both  methods,  that  the 
lead  pencil  marks  made  on  such  ground  labels  may  be 
effaced  during  the  test  if  the  bottles  are  not  carefully 
handled.  Small  strips  of  tin  or  copper  with  a  number 
stamped  thereon  are  sometimes  attached  to  a  collar 
around  the  necks  of  the  bottles.  They  are,  however, 
easily  lest,  especially  when  the  top  of  the  bottle  is 

1  A  flat-bore  test  bottle  and  one  with  a  brass  collar  and  screw  used 
for  opening  and  closing  a  small  hole  in  the  neck  of  the  test  bottle  have 
been  placed  on  the  market  by  an  Eastern  manufacturer.  These  have 
been  tried  by  us,  and  were  not  found  to  possess  any  particular  advan- 
tage over  the  round-neck  bottles;  in  fact,  are  more  subject  to  errors  of 
calibration. 


40  Testing  Milk  and  Its  Products. 

slightly  broken,  or  at  any  rate,  are  soon  corroded  so 
that  the  numbers  can  only  be  seen  with  difficulty. 

The  best  and  most  permanent  label  for  test  bottles  is 
made  by  scratching  a  number  with  a  marking  diamond 

on  the  glass  di- 
rectly above  the 
scale  on  the  neck 
of  the  bottles  or 
by  grinding  a 
number  on  the 
bottle  itself.  In 
ordering  an  "  out- 
fit, or  test  bottles 
alone,  the  oper- 
—  ator  may  specify 

FIG.  12.    Waste-acid  jar.  that     the     bottles 

are  to  be  marked  1  to  24,  or  as  many  as  are  bought, 
and  the  dealer  will  then  put  the  numbers  on  with  a 
marking  diamond. 

A  careful  record  should  be  kept  of  the  number  of  the 
bottle  into  which  each  particular  sample  of  milk  is 
measured.  Mistakes  are  often  made  when  the  operator 
trusts  to  his  memory  for  locating  the  different  bottles 
tested  at  the  same  time. 

46.  Cleaning  test  bottles.  The  fat  in  the  neck  of 
the  test  bottles  must  be  liquid  when  these  are  cleaned. 
In  emptying  the  acid  the  bottle  should  be  shaken  in 
order  to  remove  the  white  residue  of  sulfate  of  limr, 
etc.,  from  the  bottom;  if  the  acid  is  allowed  to  drain 
out  of  the  bottle  without  shaking  it,  this  residue  will 
be  found  to  stick  very  tenaciously  to  the  bottom  of  the 
bottle  in  the  subsequent  cleaning  with  water. 


The  Babcock  Test. 


41 


A  convenient  method  of  emptying  test  bottles  is  shown 
in  the  illustration  (fig.  12).  After  reading  the  fat  col- 
umn, the  bottles  are  placed  neck  down,  in  the  half-inch 
holes  of  the  board  cover  of  a  five-gallon  stoneware  jar. 


FIG.  13.  Apparatus  for  cleaning  test  bottles.  A,  apparatus  in  posi- 
tion; the  water  flows  from  the  reservoir  through  the  iron  pipe  b  into 
the  inverted  test  bottle  d  through  the  brass  tube  c,  screwed  into  the 
iron  pipe.  B  shows  construction  of  the  rubber  support  on  which  the 
test  bottles  rest;/,  sink. 

An  occasional  shaking  while  the  liquid  is  running  from 
the  bottles  will  rinse  off  the  preciptate  of  sulfate  of 
lime.  A  thorough  rinsing  with  boiling  hot  water  is 


42 


Testing  Milk  and  Its  Products. 


generally  sufficient  to  remove  all  grease  and  dirt,  as 
well  as  acid  solution  from  the  inside  of  the  bottles. 
The  apparatus  shown  in  fig.  13  will  be  found  convenient 
for  this  purpose.  After  the  bottles  have  been  rinsed  a 
second  time,  they  may  be  placed  in  an  inverted  posi- 
tion to  drain,  on  a  galvanized  iron  rack,  as  shown  in 
fig.  14,  where  they  are  kept  until  needed.  The  outside 

of  the  bottles  should 
occasionally  be  wiped 
clean  and  dry. 

47.  The  amount  of 
unseen  fat  that  clings 
to  test  bottles  used 

FIG.  14.    Draining-rack  for  test  bottles.    for     testing     milk     or 

cream,  is  generally  not  sufficient  to  be  noticed  in  test- 
ing whole  milk,  but  it  plays  an  important  part  in  test- 
ing samples  of  separator  skim  milk.  It  may  be  readily 
brought  to  light  by  making  a  blank  test  with  clean 
water  in  bottles  used  for  testing  ordinary  milk,  which 
have  been  cleaned  by  simply  draining  the  contents  and 
rinsing  once  or  twice  with  hot  water;  at  the  conclusion 
of  the  test  the  operator  will  generally  find  that  a  few 
drops  of  fat  will  collect  in  the  neck  of  the  bottles,  some- 
times enough  to  condemn  a  separator. 

Boiling  hot  water  will  generally  clean  the  grease  from 
glassware  for  a  time,  but  all  test  bottles  should,  in  ad- 
dition, be  given  an  occasional  bath  in  some  weak  alkali 
or  other  grease-dissolving  solution.  Persons  doing  con- 
siderable milk  testing  will  find  it  of  advantage  to  pro- 
vide themselves  with  a  small  copper  tank,  fig.  15, 
which  can  be  filled  with  a  weak  alkali-solution.  After 


The  Babcock  Test. 


43 


having  been  rinsed  with  hot  water,  the  test  bottles  are 
placed  in  the  hot  solution  in  the  tank,  where  they  may 
be  left  completely  covered  with  the  liquid.  If  the  tank 
is  provided  with  a  small  faucet  at  the  bottom,  the  liquid 
can  be  drawn  off  when  the  test  bottles  are  wanted.  A 
tablespoonful  of 
some  cleaning  pow- 
der to  about  two 
gallons  of  water 
will  make  a  very 
satisfactory  solu- 
tion ;  sal  soda, 
Gold  Dust,  Lewis9 
lye  or  Babbitt's 
potash  are  very 
efficient  for  this 
purpose.  The 
cleansing  proper- 
ties of  solutions  of 
any  of  these  sub- 
stances  are  in- 
creased by  warm- 
ing the  liquid.  The  FIG'15'  Tank  for  cleaning  test  bottles. 

test  bottles  must  be  rinsed  twice  with  hot  water  after 
they  are  taken  from  this  bath. 

An  excellent  cleaning  solution  that  can  be  used  for 
a  long  time,  may  be  made  of  one-half  pound  bichromate 
of  potash  to  one  gallon  of  sulfuric  acid.1 

An  arrangement  for  cleaning  a  number  of  test  bot- 
tles at  the  same  time  is  shown  in  fig.  16. 2  III  shows  the 

1  Michels,  Am.  Cheesemaker,  Jan.  1903. 

2  Wisconsin  experiment  station,  bull.  129. 


44 


Testing  Milk  and  Its  Products. 


frame  in  which  the  "bottles  are  placed,  one  in  each 
socket;  the  metal  plate  E  is  put  over  the  necks  of  the 
bottles  which  pass  through  the  holes  in  it  up  to  the 
shoulder  of  the  bottles.  The  pins  F,  F,  are  then  pushed 
through  holes  in  the  rods  D-D,  and  the  plate  and  bot- 
tles are  thus  firmly  held  in  the  crate.  When  secured  in 


FIG.  16.    A  convenient  devise  for  cleaning  test  bottles. 

this  way,  the  frame  full  of  bottles  may  be  placed  in  a 
pail  or  tank  of  hot  water  as  in  I.  They  will  soon  fill 
with  water  and  the  time  of  filling  the  bottles  one  at  a 
time  thus  saved.  When  ready  to  empty  the  bottles,  the 
frame  is  reversed  and  placed  in  the  position  shown  in  II. 
One  or  two  rinsings  in  boiling  hot  water  is  usually 
sufficient  to  effectually  clean  the  bottles,  but  when  they 
have  been  allowed  to  get  greasy  they  can  be  dipped  into 
a  pail  of  hot  dilute  lye;  this  will  saponify  the  grease 
and  after  one  or  two  rinsings  in  clean  hot  water  the 
bottles  will  be  bright  and  clean. 


The  Babcock  Test.  45 

The  black  stains  that  sometimes  stick  to  the  inside  of 
test  bottles  after  prolonged  use,  can  be  removed  with  a 
little  muriatic  acid,  or  by  means  of  a  small  stiff  brush. 
48.  Pipette.  The  difference  in  the  weights  of  various 
samples  of  normal  milk  generally  falls  within  compara- 
tively narrow  limits ;  if  a  given  volume  of  water  weighs 
one  pound,  the  same  volume  of  the  usual  grades  of  nor- 
mal milk  will  weigh  frcm  1.029  to  1.033  pounds,  or  on 
the  average,  1.03  Ibs.  18  grams  of  water  measures  18 
cc.1 ;  18  grams  of  milk  will  therefore  take  up  a  smaller 
volume  than  18  cc.,  viz.,  18  divided  by  1.03,  which  is 
\vry  nearly  17.5.  This  is  the  quantity  of  milk  taken 
in  the  Babcock  test.  A  certain  amount  of 
milk  will  adhere  to  the  walls  of  the  pi- 
pette when  it  is  emptied,  and  this  thin  film 
has  been  found  to  weigh  about  one-tenth' 
of  a  gram;  consequently  17.6  cc.  has  been 
adopted  as  the  capacity  of  the  pipette  used 
for  delivering  18  grams  of  milk. 

r\  LJ 

For  convenience  in  measuring  the  milk, 

FIG.  17.    Pipette 

points—  the  shape  of  the  pipette  is  of  importance. 

A,     proper  con- 

,  Pi  The  mark  on  the  stem  should  be  two  inches 


construction.     Qr   more    from   the   upper   end    of    the    pip_ 

ette.  The  lower  part  should  be  small  enough  to  fit 
loosely  into  the  neck  of  the  test  bottle,  and  not  con- 
tracted to  a  fine  hole  at  the  point ;  the  point  should  be 

-1  Cubic  centimeters  (abbreviated:  cc.)  are  the  standard  used  for 
measuring  volume  in  the  metric  system,  similar  to  the  quart  or  pint 
measure  iii  our  ordinary  system  of  measures.  One  quart  is  equal  to  a 
little  less  than  1,000  cubic  centimeters  (1  liter).  In  the  same  way,  grams 
represent  weight,  like  pounds  and  ounces.  One  cc.  of  water  at  ^Centi- 
grade weighs  1  gram;  1,000  grams  <  =  1  kilogram)  are  equal  to  2.2  Ibs." 
Avoirdup.  (See  Appendix  for  Comparisons  of  metric  and  customary 
weights  and  measures.) 


46  Testing  Milk  and  Its  Products. 

large  enough  to  allow  a  quick  emptying  of  the  pipette 
(fig.  17)  and  not  so  large  that  it  is  difficult  to  use  it. 
An  opening  of  less  than  %  in.  diameter  will  be  found 
satisfactory. 

49.  Fool  pipettes.    Soon  after  the  Babcock  test  began  to  be 
generally  used  at  creameries  as  a  basis  of  payment  for  the  milk, 
a  creamery  supply  house  put  on  the  market  a  20  cc.  milk-meas- 
uring pipette,  which  was  claimed  to  show  the  exact  butter  value 
of  milk,  instead  of  its  content  of  butter   fat,  as  is   the  case  in 
using  the   ordinary   17.6   cc.   pipette.     A   20   cc.   pipette   will   de- 
liver 2.4  ct.  more  milk  than  a  17.6  cc.  pipette,   (or  13.6  per  cent, 
more),    and   the    results    obtained   by   using    these    pipettes   will, 
therefore,  be  about  13.6  per  cent,  too  high.     In  considering  the 
subject  of  Overrun   (214)    it  is  noted  that  the  excess  of  butter 
yield  over  the  amount  of  fat  contained  in  a  certain  quantity  of 
milk  will  range  from  about  10  to  16  per  cent.,  or  on  the  average, 
about  12  per  cent.     20  cc.  pipettes  may,  therefore,  give  approxi- 
mately  the   yield   of  butter   obtained   from   a   quantity   of   milk, 
but  as  will  be  seen,  this  yield  is  variable,  according  to  the  skill 
of  the  butter  maker  and  according  to  conditions  beyond  his  con- 
trol; it  cannot  therefore  be  used  as  a  standard  in  the  same  man- 
ner as  the  fat  content  of  the  milk.     Similar  22  cc.  pipettes  were 
also  sent  out.     These  pipettes  created  a  great  deal  of  confusion 
during  the  short  time  they  were  on  the  market,  and  were  popu- 
larly  termed  "fool"   pipettes.     It  is  not  known  that   such   pi- 
pettes  have   been   sold   of  late   years. 

A  recent  Wisconsin  law  makes  it  a  misdemeanor  to  use  in 
that  state  other  than  17.6  cc.  pipettes  for  measuring  milk  where 
this  is  paid  for  by  the  Babcock  test.1 

50.  Acid  measures.    A  17.5  cc.  glass  cylinder  (fig.  9) 
for  measuring  the  acid  is  generally  included  in  the  out- 
fit, when  a  Babcock  tester  is  bought.     This  cylinder  an- 
swers every  purpose  if  only  occasional  tests  are  made; 
the  acid  is  poured  into  the  cylinder  from  the  acid  bottle 
as  needed,  or  a  quantity  of  acid  sufficient  for  the  num- 
ber of  test  bottles  to  be  whirled  at  a  time,  is  poured 

l  Laws  of  1903,  chapter  48. 


The  Babcock  Test. 


into  a  small  glass  beaker  provided  with  a  lip,  or  into  a 
small  porcelain  pitcher;  these  may  be  more  easily 
handled  than  the  heavy  acid  bottle  or  jug,  and  the  acid 
measure  is  then  filled  from  such  a  vessel. 

Where  a  considerable  number  of  tests  are  made  regu- 
larly, the  acid  can  be  measured  into  the  test  bottles 
faster  and  with  less  danger  of  spilling,  by  using  some 
one  of  the  many  devices  proposed  for  this  purpose. 
There  is  some  objection  to  nearly  all  of  these  appliances, 
automatic  pipettes,  burettes,  etc.,  although  they  will 
often  give  good  satisfaction  for  a  time  while  new.  Sul- 
furic  acid  is  very  corrosive, 
and  operators,  as  a  rule,  take 
but  poor  care  of  such  appara- 
tus, so  that  it  is  a  very  diffi- 
cult matter  to  design  a  form 
which  will  remain  in  good 
working  order  for  any  length 
of  time.  Automatic  pipettes 
attached  to  acid  bottles  or  res- 
ervoirs, to  prove  satisfactory, 
must  be  made  entirely  of  glass, 
and  strong,  of  simple  construc- 
tion, tightly  closed  and  quickly 
operated. 

51.  The  Swedish  acid  bot- 
tle answers  these  requirements     the  side  tube  is  made  to  hold 
better  than   any  other  device     17'5cc'°f 
known  to  the  writers  at  the  present  time.     Its  use  is 
easily  understood   (see  fig.  18)  ;  it  gives  good  satisfac- 
tion if  the  hole  in  the  glass  stop-cock  through  which  the 


FIG. 


Swedish  acid-bottle; 


48  Testing  Milk  and  Its  Products. 

acid  passes  has  a  diameter  of  at  least  one-eighth  of  an 
inch,  as  is  generally  the  case.  We  have  used  or  in- 
spected some  half  a  dozen  other  devices,  which  have 
been  placed  on  the  market  by  various  dealers  for  de- 
livering the  acid,  but  cannot  recommend  them  for  use 
in  factories  or  outside  of  chemical  laboratories. 

52.  Instead  of  measuring  out  the  acid,  Bartlett1  has  suggested 
adding  20  cc.  directly  to  the  milk  in  the  test  bottles,  till  the  mix- 
ture rises  to  a  mark  on  the  body  of  the  bottle  at  the  point 
where  this  will  hold  37.5  cc.,  i.  e.,  the  total  volume  of  milk  and 
acid  (83).  This  method  of  adding  the  acid  is  in  the  line  of  sim- 
plicity, but  has  not  become  generally  adopted.  If  the  method  is 
used,  the  marks  should  be  put  on  by  the  manufacturers,  as  the 
operator  in  attempting  to  do  so  will  be  apt  to  weaken  or  break 
the  bottles. 

CALIBRATION  OF  GLASSWARE. 

53.  Test  bottles.     The  Babcock  milk  test  bottles  are 
so  constructed  that  the  scale  of  graduation  on  the  neck 
measures  a  volume  of  2  cubic  centimeters,  between  the 
zero  and  the  10  per  cent,  marks  (44).     The  standards 
adopted  by  Eastern  experiment  stations  for  test  bottles 
and  other  Babcock  glassware  are  given  at  the  close  of 
this  book  (306).    It  will  be  seen  that  the  limit  of  error 
for  test  bottles  is  one  of  the  smallest  graduations  on  the 
scale,  or  .2  per  cent.     The  correctness  of  the  gradua- 
tions may  be  easily  ascertained  by  one  of  the  following 
methods : 

54.  (A.)   Calibration  with  water.    This  may  be  done 
by  means  of  a  delicate  pipette  or  burette,  or  by  weigh- 
ing the  water  that  the  graduated  portion  of  the  neck 
will  hold. 

1  Maine  «'\p<>rim<'nt  station,  bull.  31. 


The  Babcock  Test.  49 

a,  Measuring  the  water.     Fill  the  test  bottle  with 
water  to  the  zero  mark  on  the  scale;  remove  any  sur- 
plus water  and  dry  the  inside  of  the  neck  with  a  piece 
of  filter  paper  or  clean  blotting  paper;  then  measure 
into  the  bottle  2  cc.  of  water  from  an  accurate  pipette 
or  burette,  divided  to   -I   of  a  cubic  centimeter.    If  the 
graduation  is  correct,  2  cc.  will  fill  the  neck  exactly  to 
the  10  per  cent,  mark  of  the  scale. 

b,  Weighing  the  water.     Fill  the  bottle  with  water 
to  the  zero  mark  of  the  scale  and  remove  any  surplus 
water  in  the  neck,  as  before.    Weigh  the  bottle  with  the 
water  contained  therein.     Now  fill  the  neck  with  water 
to  the  10  per  cent,  mark,  and  weigh  again.     The  differ- 
ence between  these  weights  should  be  2  grams. 

In  all  cases  where  calibrations  are  to  be  made,  the 
test  bottles,  or  other  glassware  to  be  calibrated,  must  be 
thoroughly  cleaned  beforehand  with  strong  sulfuric 
acid  or  soda  lye,  and  washed  repeatedly  with  pure 
water,  and  dried.  Glassware  is  not  clean  unless  water 
will  run  freely  over  its  surface,  without  leaving  any 
adhering  drops. 

55-  (B).  The  Trowbridge  method  of  calibration.1 
An  extremly  simple  and  accurate  method  of  calibrating 
test  bottles  has  been  proposed  by  Mr.  0.  A.  Trowbridge 
of  Columbus,  Wis.  He  conceived  the  idea  of  measur- 
ing the  capacity  of  the  graduated  portion  of  the  neck 
of  a  milk  test  bottle  with  a  piece  of  metal  which  is  care- 
fully filed  to  such  a  size  that  it  will  displace  exactly 
two  cubic  centimeters  of  water.  He  used  a  thirty-penny 
wire  nail,  cutting  off  the  head  of  the  nail  and  attaching 

1  Hoard's  Dairyman,  Mar.  8,  1901,  by  DeWltt  Goodrich. 

4 


50  Testing  Milk  and  Its  Products. 

to  it  a  short  piece  of  fine  wire.  Manufacturers  have 
improved  on  this  rather  crude  device  and  standard 
measures  for  calibrating  test  bottles  may 
now  be  bought  of  any  dairy  supply  house 
(see  fig.  19). 

When  a  test  bottle  is  to  be  calibrated 
by  this  standard  measure,  it  is  filled  with 
water  to  the  zero  mark  on  the  neck  of  the 
bottle.  The  water  adhering  to  the  neck  is 
carefully  removed  with  a  strip  of  blotting 
paper,  and  the  measure  is  then  lowered 
into  the  test  bottle,  as  shown  in  the  illus- 
tration. If  the  water  rises  from  0  to  10 
on  the  neck  when  the  upp  r  point  of  Ihe 
measure  is  submerged  in  the  water,  the 
scale  is  correct.  If  greater  variations  than 
.2  per  cent,  occur,  the  bottle  should  be  re- 
jected. 

The  figure  shows  one  of  these  calibrator 
made  in  two  sections,  so  that  the  accuracy 
of  the  5  per  cent.,  as  well  as  the  10  per- 
cent, mark  on  the  scale  may  he  ascer- 
tained. 

56.  The  standard  measure.  In  the  place 
of  an  iron  nail,  as  originally  proposed,  a 
FIG.  19.    The  piece  of  metal  or  glass  rod  may  be  adv«n- 

Trowbridge 

calibrator.  tageously  used  as  a  standard  measure.  1  he 
standardization  of  this  measure  is  most  conveniently 
done  by  weighing.  Since  the  specific  gravities  of  iron. 
copper,  brass,  and  glass  are  7.2,  8.7,  8.5,  and  about  2.7, 
respectively,  pieces  of  these  materials  replacing  2  cc.  of 


The  Babcock  Test.  51 

a  liquid,  will  weigh  14;,  17.4,  17.0  and  5.4  grams,  for 
iron,  copper,  brass  and  glass  in  the  order  given. 

A  measure  of  the  right  weight  may  be  suspended  by 
a  very  fine  copper  or  platinum  wire  (melted  into  the 
glass  rod  if  this  material  be  chosen),  and  is  used  di- 
rectly for  calibrating  test  bottles  as  described  above. 
Before  a  measure  so  made  is  used  as  a  standard,  its  ac- 
curacy should  be  determined  by  weighing  the  amount 
of  water  of  a  temperature  of  17.5°  C,  which  it  replaces. 
The  specific  gravity  of  glass  especially,  varies  somewhat 
according  to  its  composition,  so  that  a  standardization 
of  a  measure  by  weight  alone  cannot  be  depended  upon 
to  always  give  correct  results. 

In  submerging  the  measure  in  the  test  bottle  to  be 
calibrated,  care  must  be  taken  that  all  air  bubbles  are 
removed  before  the  position  of  the  meniscus1  of  the 
water  is  noted;  if  a  metal  standard  measure  is  used,  it 
must  be  kept  free  from  rust  or  tarnish. 

57.  (C.)  Calibration  with  mercury.  27.10  grams  of 
metallic  mercury  are  weighed  into  the  perfectly  clean  and  dry 
test  bottle.  Since  the  specific  gravity  of  mercury  is  13.55, 
double  this  quantity  will  occupy  a  volume  of  exactly  2  cubic 
centimeters  (48).  The  neck  of  the  test  bottle  is  then  closed 
with  a  small,  smooth  and  soft  cork,  or  a  wad  of  absorbent  cot- 
ton, cut  off  square  at  one  end,  the  stopper  being  pressed  down 
to  the  first  line  of  the  graduation.  The  bottle  is  now  inverted 
so  that  the  mercury  will  run  into  its  neck.  If  the  total  space 
included  between  the  0  and  10  marks  is  just  filled  by  the  two 
cubic  centimeters  of  mercury,  the  graduation  is  correct.  Bot- 
tles, the  whole  length  of  the  scale  of  which  vary  more  than  two- 
tenths  of  one  per  cent.,  are  inaccurate  and  should  not  be  used. 

The  mercury  may  be  conveniently  transferred  from  one  test 
bottle  to  another,  by  means  of  a  thin  rubber  tube  which  is 
slipped  over  the  end  of  the  necks  of  both  bottles,  and  one  weigh- 


52  Testing  Milk  and  Its  Products. 

ing  of  mercury  will  thus  suffice  for  a  number  of  calibrations. 
In  transferring  the  mercury,  care  must  be  taken  that  none  of  it 
is  lost,  and  that  small  drops  of  mercury  are  not  left  sticking  to 
the  walls  of  the  bottle  emptied.  A  sharp  tap  on  the  bottle 
with  a  lead  pencil  will  help  to  remove  minute  drops  of  mercury 
from  the  inside.  Unless  the  bottles  to  be  calibrated  are  per- 
fectly clean  and  dry,  it  is  impossible  to  transfer  all  the  mer- 
cury from  one  bottle  to  another. 

After  several  calibrations  have  been  made,  the  mercury  should 
be  weighed  again  in  order  to  make  certain  that  none  has  been 
lost  by  the  various  manipulations.  Scales  similar  to  those  shown 
in  figs.  34  and  35  (91)  are  sufficiently  delicate  for  making  these 
weighings. 

58.  Test  bottles  may  also  be  calibrated  with  mercury  by  weigh- 
ing the  bottles  filled  with  mercury  to  the  zero  mark,  and  again 
when  filled  to  the  10  mark.     This  is  the  official  method  for  test- 
ing bottles   adopted   by   Eastern    states    (see   306). 

59.  Cleaning  mercury.  Even  with  the  best  of  care,  mercury 
used   for   calibration   of   glassware   will   gradually  become  dirty, 
so  that  it  will^not  flow  freely  over  a  clean  surface  of  glass.     It 
may  be  cleaned  from  mechanical  impurities,  dust,  grease,  water, 
etc.,  by  filtration  through  heavy  filter  paper.     This  is  folded  in 
the  usual  way,  placed  in  an  ordinary  glass  funnel  and  its  point 
perforated  with  a  couple  of  pin  holes.     The  mercury  will   pass 
through    in    fine    streams,    leaving    the    impurities    on    the    filter 
paper.     Mercury  may  be   freed   from   foreign  metals,   zinc,   lead, 
etc.,    sometimes   noticed   as   a   grayish,    thin   film    on    its   surface, 
by  leaving  it  in  contact  with  common  nitric  acid  for  a  number 
of  hours;   the  mercury  is  best  placed   in   a   shallow   porcelain   or 
graniteware    dish   and   the   nitric    acid   poured    over   it,    the    dish 
being  covered  to  keep  out  dust.     The  acid  solution  is  then  care- 
fully poured  off  and  the  mercury  washed  with  water;   the  latter 
is  in  turn  poured  off,  and  the  last  traces  of  water  absorbed  by 
means  of  clean,  heavy  filter  paper. 

The  mercury  to  be  used  for  calibration  of  glassware  should 
be  kept  in  a  strong  bottle,  closed  by  an  ordinary  stopper.  In 
handling  mercury,  care  must  be  taken  not  to  spill  any  portion 
of  it;  finger-rings  should  be  removed  when  calibrations  with  mor- 
cury  are  to  be  made. 


The  Babcock  Test.  53 

Mercury  forms  the  most  satisfactory  and  accurate  material 
for  calibration  of  test  bottles,  on  account  of  its  heavy  weight 
and  the  ease  with  which  it  may  be  manipulated.  Equally  correct 
results  may,  however,  with  proper  care  be  obtained  by  using 
water  for  the  calibration. 

60.  Intermediate   divisions.     The  space  between   0 
and  10  on  the  scale  of  the  Babcock  test  bottle  is  divided 
into   50   divisions,    each   five   of   which,    as   previously 
shown,   represent   1  per  cent.    (44).     Since  these  in- 
termediate divisions  are  generally  made  with  a  dividing 
machine,  they  are  as  a  rule  correct,  but  it  may  happen 
that  they  have  been  inaccurately  placed,  although  the 
space  between  0  and  10  is  correct.    The  accuracy  of  the 
intermediate   divisions   can   be   ascertained   by   sliding 
along  the  scale  a  strip  of  paper  upon  which  has  been 
marked  the  space  occupied  by  one  per  cent,  and  com- 
paring this  space  with  those  of  each  per  cent,  on  the 
scale. 

61.  Calibration    of    skim    milk    test    bottles.      The 
value  of  each  division  on  the  common   double-necked 
skim  milk  bottles  (99)   is  one-twentieth,  or  .05  of  one 
per  cent. ;  there  are  ten  of  these  divisions  in  the  whole 
scale  which,  therefore,  measures  .5  per  cent,  of  fat.    It 
requires  very  careful  work  to  calibrate  this  scale  and  it 
is  best  done  by  weighing  the  amount  of  mercury  which 
will  just  fill  the  space  of  1  cc.  between  the  first  and  the 
last  divisions   (53)  ;  the  correct  weight  of  this  mercury 
is  1.359  grams. 

62.  Calibrating  cream  test  bottles.     The  cream  bot- 
tles may  be  calibrated  by  any  of  the  methods  given  for 
milk  bottles.    The  neck  of  a  cream  test  bottle  that  meas- 
ures thirty  per  cent,  fat  will  hold  6  cc.,  and  6  grams  of 
water  or  81.54  grams  of  mercury. 


54  Testing  Milk  and  Its  Products. 

The  Trowbridge  method  of  calibrating  milk  test  bot- 
tles may  also  be  found  convenient  for  cream  bottles  and 
the  same  standard  measure  used,  the  part  of  the  scale 
from  0  to  10  being  calibrated  first,  then  that  from  10  to 
20,  and  from  20  to  30  per  cent,  in  the  same  way. 

63.  Pipette  and  acid  cylinder.    The  pipette  and  the 
acid  cylinder  used  in  the  Babcock  test  may  be  calibrated 
by  any  of  the  methods  already  given.     Sufficiently  ac- 
curate results  are  obtained  by  weighing  the  quantity  of 
water  which  each  of  these  pieces  of  apparatus  will  hold, 
viz.,   17.6    grams   and    17.5   grams,   respectively.      The 
necessity  of  previous  thorough  cleaning  of  the  glassware 
is  evident  from  what  has  been  said  in  the  preceding. 
The  pipette  and    the    acid    measure  may  be  weighed 
empty   and  then  again  when  filled  to  the  mark  with 
pure  water,  or  the  measureful  of  water  may  be  emptied 
into  a  small  weighed  vessel,  and  this  weighed  a  second 
time.    In  either  case  the  weight  of  the  water  contained 
in  the  pipette  or  acid  measure  is  obtained  by  difference.1 

Calibrations  of  the  acid  cylinder  are  generally  not 
called  for,  except  as  a  laboratory  exercise,  since  small 
variations  in  the  amount  of  acid  measured  do  not  affect 
the  accuracy  of  the  test. 

2.— CENTRIFUGAL  MACHINES. 

64.  The  capacity  of  the  testing  machine  to  be  selected 
should  be  governed  by  the  number  of  tests  which  are 
likely  to  be  made  "at  one  time.    For  factory  purposes  a 

1  One  cubic  centimeter  of  distilled  water  weighs  1  grnm,  when 
weighed  In  a  vacuum  at  the  temperature  of  the  maximum  density  of 
water  (4°O);  for  the  purpose  of  calibration  of  glassware  used  in  the 
Babcock  test,  sufficiently  accurate  results  are,  however,  obtained  by 
weighing  the  water  in  the  air  and  at  a  low  room  temperature  (60°  F.) 


The  Babcock  Test.  55 

twenty-four  or  a  thirty-two  bottle  tester  is  large  enough, 
and  to  be  preferred  to  a  larger  tester,  even  if  a  large 
number  of  samples  are  to  be  tested  at  a  time.  The 
operator  can  use  his  time  more  economically  in  running 
a  machine  of  this  size  than  one  holding  fifty  or  sixty 
bottles;  the  work  of  filling  or  cleaning  the  bottles  and 
measuring  the  fat  can  be  done  while  the  tester  is  run- 
ning if  a  double  supply  of  bottles  is  at  hand.  Large 
testers  require  more  power  than  smaller  ones,  and  when 
sixty  tests  are  made  at  a  time,  the  fat  column  in  many 
bottles  will  get  cold,  before  the  operator  has  time  to 
read  them,  unless  special  precautions  are  taken  for 
keeping  the  bottles  warm. 

65.  The  tester  should  be  securely  fastened  to  a  solid 
foundation  and  set  so  that  the  revolving  wheel  is  level. 
The  latter  must  be  carefully  balanced  in  order  that  the 
tester  may  run  smoothly  at  full  speed  when  empty.  A 
machine  that  trembles  when  in  motion  is  neither  sat- 
isfactory nor  safe,  and  the  results  obtained  are  apt  to 
be  too  low.  High-standing  machines  are  more  likely  to 
cause  trouble  in  this  respect  than  low  machines,  and 
should  therefore  be  subjected  to  a  severe  test  before 
they  are  accepted. 

If  all  sockets  are  not  filled  with  bottles  when  a  test 
is  to  be  made,  the  bottles  must  be  placed  diametrically 
opposite  one  another  so  that  the  machine  will  be  bal- 
anced when  run.  The  bearings  should  be  kept  cleaned 
and  oiled  with  as  much  care  as  the  bearings  of  a  cream 
separator. 

The  cover  of  the  machine  should  always  be  kept 
closed  while  the  bottles  are  whirled,  and  should  not  be 


56  Testing  Milk  and  Its  Products. 

removed  until  the  machine  stops;  it  should  be  tight 
fitting,  since  test  bottles  sometimes  break  while  the  ma- 
chine is  running  at  full  speed,  and  every  possible  pre- 
caution should  be  taken  to  protect  the  operator  from 
any  danger  from  spilled  acid  or  broken  glass. 

66.  Speed  required  for  the  complete  separation  of 
the  fat.  There  is  a  definite  relation  between  the  diame- 
ter of  the  Babcock  testers  and  the  speed  required  for  a 
perfect  separation  of  the  fat.  In  the  preliminary  work 
with  the  Babcock  test  the  inventor  found  that  with  the 
machine  used,  the  wheel  of  which  had  a  diameter  of 
eighteen  inches,  it  was  necessary  to  turn  the  crank,  so 
as  to  give  the  test  bottles  seven  or  eight  hundred  revo- 
lutions per  minute,  in  order  to  obtain  a  maximum  sepa- 
ration of  fat;  later  work  has  shown  that  this  speed  is 
ample.  Taking  therefore  this  as  a  standard,  the  centri- 
fugal force  to  which  the  contents  of  the  test  bottles  are 
subjected  when  supported  on  an  eighteen-inch  wheel 
and  turned  800  revolutions  per  minute,  can  be  calcu- 
lated as  follows: 

The  centrifugal  force,  F,  acting  on  the  bottles  is  expressed  by 
the  formula 


in  which  w  —  the  weight  of  the  bottle  with  contents,  in  pounds; 
v  =  the  velocity,  in  feet  per  second,  and  r  =  the  radius  of  the 
wheel  in  feet. 

When  the  wheel  is  turned  800  times  a  minute,  a  bottle  sup- 
ported on  its  rim  will  travel  2?rrX  8e°0°=2x3.1415XftX%0:r::62-83 
feet  per  second.  The  weight  of  a  bottle,  with  milk  and  acid,  is 
about  3  ounces,  or  fa  of  a  pound.  Substituting  these  values 
for  v  and  w,  gives 


The  Babcock  Test.  57 


The  bottles  are,  therefore,  under  the  conditions  given,  sub- 
jected to  a  pressure  of  about  30.65  pounds.  In  order  to  calcu- 
late the  speed  required  for  obtaining  this  force  in  case  of  ma- 
chines of  other  diameters,  the  value  of  v  in  formula  (I)  is 
found  from 


32-2 


Substituting  the  values  for  F  and  w,  we  have 


/32.2X30.65r          /— — 
v=]/  — j —  =i/o264r 

In  this  equation  the  values  r  =  5,  6,  7,  8,  9,  10,  11,  12  inches 
are  substituted  in  each  case  (T5.,,  ^  /f,  .  .  .  JJ  feet),  and  the 
velocity  in  feet  per  second  then  found  at  which  the  bottles  are 
whirled  when  placed  in  wheels  of  diameters  10  to  24  inches,  and 
subjected  in  each  case  to  a  centrifugal  force  of  30.65  Ibs.  As 

the  number  of  revolutions  per  minute  =7r-    -,  v  being  as  before 

2  Trr 

the  velocity  in  feet  per  second,  and  r  the  radius  of  the  wheel, 
the  speed  at  which  the  wheel  must  be  turned  is  found  by  sub- 
stituting for  v  the  values  obtained  in  the  preceding  calculations 
in  case  of  wheels  of  different  diameters.  The  results  of  these 
calculations  are  given  in  the  following  table: 

Diameter  Velocity  in  feet  Number  of  revolutions 

of  wheel,  D.  per  second,  v.  of  wheel  per  minute. 

10                                       46.84  1074 

12                                        51.31  980 

14                                       55.43  909 

16                                       59.26  848 

18                                       62.84  800 

20                                       66.24  759 

22                                       69.47  724 

24                                       72.56  693 
These   figures    show   that   a   tester,   for   instance,   24   inches   in 

diameter,    requires   less   than   700  revolutions   per   minute    for    a 

perfect  separation  of  the  fat  in  Babcock  bottles,  while  a  ten- 
inch  tester  must  have  a  speed  of  nearly  1100  revolutions,  in 
order  to  obtain  the  same  result. 


58  Testing  Milk  and  Its  Products. 

The  speed  at  which  testers  of  different  diameters  should  be 
run  to  effect  a  complete  separation  has  been  calculated  by  Prof. 
C.  L.  Beach  in  the  following  manner.1  The  same  standard  as 
before  is  taken,  viz.,  800  revolutions  for  an  18-inch  tester  (radius 
9  inches)  ;  then  if  x  designate  the  radius  of  the  tester  and  y  the 
speed  required,  we  have 


V 


The  figures  obtained  by  the  use  of  this  formula  are  similar 
to  those  given  in  the  preceding  table. 

67.  To  find  the  number  of  turns  of  the  handle  corre- 
sponding to  the  number  of  revolutions  made  by  the 
wheel,  the  handle  is  given  one  full  turn,  and  the  number 
of  times  which  a  certain  point  or  part  of  the  wheel  re- 
volves, is  noted.  If  the  wheel  has  a  diameter  of  20 
inches,  and  revolves  12  times  for  one  turn  of  the  handle, 
the  latter  should  be  turned  M>==63  times  a  minute  (see 

12 

table),  or  about  once  every  second,  in  order  to  effect  a 
maximum  separation  of  fat.  By  counting  the  number  of 
revolutions,  watch  in  hand,  and  consulting  the  preceding 
table,  the  operator  will  soon  note  the  speed  which  must 
be  maintained  in  case  of  his  particular  machine.  It  is 
vitally  important  that  the  required  speed  be  always 
kept  up ;  if  through  carelessness,  worn-out  or  dry  bear- 
ings, low  steam  pressure,  etc.,  the  speed  is  slackened,  the 
results  obtained  will  be  too  low ;  it  may  be  a  few  tenths, 
or  even  more  than  one  per  cent.  Care  as  to  this  point 
is  so  much  the  more  essential,  as  the  results  obtained 
by  too  slow  whirling  may  seem  to  be  all  right,  a  clear 

1  Private  communication. 


The  Babcock  Test.  59 

separation  of  fat  being  often  obtained,  even  when  the 
fat  is  not  completely  separated. 

68.  Ascertaining  the  necessary  speed  of  testers.  In 

buying  a  tester  the  operator  should  first  of  all  satisfy 
himself  at  what  speed  the  machine  must  be  run  to  give 
correct  results ;  the  preceding  table  will  serve  as  a  guide 
on  this  point.  He  should  measure  out  a  dozen  tests  of 
the  same  sample  of  milk,  and  whirl  half  the  number  at 
the  speed  required  for  machines  of  the  diameter  of  his 
tester.  Whirl  the  other  half  at  a  somewhat  higher 
speed.  If  the  averages  of  the  two  sets  of  determinations 
are  the  same,  within  the  probable  error  of  the  test  (say, 
less  than  one-tenth  of  one  per  cent.),  the  first  whirling 
was  sufficient,  as  it  is  believed  will  generally  be  the  case. 
If  the  second  set  of  determinations  come  higher  than  the 
first  set,  the  first  whirling  was  too  slow,  and  a  new  series 
of  tests  of  the  same  sample  of  milk  should  be  made  to 
ascertain  that  the  speed  in  the  second  set  of  determina- 
tions was  sufficient. 

This  method  will  test  not  only  the  speed  required 
with  the  particular  machine  at  hand,  but  will  also  serve 
to  indicate  the  correctness  of  the  calibration  of  the  bot- 
tles. A  large  number  of  tests  of  the  same  sample  of 
milk  made  as  directed  (pouring  the  milk  once  or  twice 
previously  to  taking  out  a  pipetteful  for  each  test) 
should  not  vary  more  than  two-tenths  of  one  per  cent, 
at  the  outside,  and  in  the  hands  of  a  skilled  operator 
will  generally  come  within  one-tenth  of  one  per  cent. 
If  greater  discrepancies  occur,  the  test  bottles  giving 
too  high  or  too  low  results  should  be  further  examined, 
and  calibrated  according  to  the  directions  already  given 
(53  et  seq.). 


60 


Testing  Milk  and  Its  Products. 


69.  Hand  testers.  When  only  a  few  tests  are  made 
at  a  time,  and  at  irregular  intervals,  as  in  case  of  dairy- 
men who  test 
single  cows  in 
their  herds,  a 
small  hand  test- 
er  answers  every 


may  be  had  in 
sizes  from  two 
to  twelve  bot- 
'tles.  In  select- 
ing a  particular 
make  of  tester 
the  dairyman 

FIG.  20.    Type  of  Babcock  hand  testers.  has     the      choice 

of  a  large  number  of  different  machines.  Most  of  the 
first  machines  placed  on  the  market  for  this  purpose 
were  so  cheaply  and 
poorly  constructed  as 
to  prove  very  unsat- 
isfactory after  hav- 
ing been  in  use  for  a 
time.  The  competi- 
tion between  manu- 
facturers of  dairy 
supplies  and  the 
clamor  of  dairymen 

for   Something   cheap,     FIG.  21.    Type  of  Babcock  hand  tester-. 

fully  accounted  for  this  condition  of  affairs.     This  ap- 
plies especially  to  the  early  machines  made  with  belts 


The  Babcock  Test.  ^  61 

or  friction  application  of  power.  Hand  testers  made 
with  cog-geared  wheels  can  be  depended  on  to  give  the 
necessary  speed  when  run  according  to  the  manufactur- 
ers' directions;  the  earlier  machines  of  this  kind  were 
very  noisy,  but  at  the  present  time  the  best  machines 
on  the  market  are  of  this  type.  These  are  provided 
with  spiral  cog-gearing  and  ball  bearings,  are  strongly 
made  and  will  run  smoothly  and  with  little  noise  (figs. 
20  and  21)  ;  in  cog-geared  machines  the  bottles  are  al- 
ways whirled  at  the  speed  which  the  number  of  turns 
made  by  the  crank  would  indicate. 

70.  Power  testers.  For  factory  purposes,  steam  tur- 
bine machines  (figs.  22-25)  are  most  satisfactory  when 
well  made  and  well  cared  for.  They  should  always  be 
provided  with  a  speed  indi- 
cator and  steam  gauge,  both 
for  the  purpose  of  knowing 
that  sufficient  speed  is  at- 
tained, and  to  prevent  what 
may  be  serious  accidents 
from  a  general  smash-up,  if 
the  turbine  "runs  wild"  by 
turning  on  too  much  steam. 
The  revolving  wheel  of  the 

tester  should  be  made  of  FlG>22<  Ty pe  of  ^abcock  steam 
wrought  or  malleable  iron,  or  lters- 

of  wire,  so  that  it  will  not  be  broken  by  the  centrifugal 
force  and  cause  accidents.  The  swinging  pockets 
.which  hold  the  test  bottles  in  some  machines  should 
be  so  made  that  the  bottles  will  not  strike  the 
center  of  the  revolving  frame  when  in  a  horizontal  posi- 


62 


Testing  Milk  and  Its  Products. 


tion.  Tests  have  often  been  lost  by  the  end  of  the  neck 
catching  at  the  center,  the  bottles  thus  failing  to  take 
an  upright  position  when  the  whirling  stops. 

71.  The  exhaust  steam  pipe  of  turbine  testers  should 
not  have  too  many  turns  in  it  or  be  much  reduced  in 
size  from  that  of  the  opening  in  the  tester.  A  free  es- 
cape of  the  exhaust  steam  is  necessary  to  prevent  the 
steam  collecting  in  the  test  bottle  chamber  and  over- 
heating the  test  bottle  when  whirled  (41). 

The  cover  of  the  tester  should  have  an  opening  pro- 
vided with  a  sliding  damper  or  some  arrangement  by 
which  it  can  be  closed  when  desired.  If  whole  milk  or 
cream  is  being  tested,  this  hole  should  be  open  so  that  a 
draft  of  air  may  enter  the  test  bottle  chamber  during  the 

whirling,  and  force 
the  steam  out  of 
the  bottle  cham- 
ber into  the  ex- 
h  a  u  s  t  pipe.  If 
skim  milk  is  being 
tested,  the  open- 
ing in  the  cover 
should  be  closed. 
This  shuts  off  the 
draft  of  air,  and 
the  exhaust  steam 
heats  the  test  bot- 
tles during  whirl- 

FIG.  23.  Type  of  Babcock  electrical  testers,        ing   to    200°    F.    in 

some  cases.  This  high  temperature  aids  in  separating 
the  fat  in  skim  milk  and  gives  fairly  correct  tests  of 


The  Babcock  Test. 


63 


FIG.  24.    Type  of  Babcock  turbine  testers  (for 
testing  cream  in9-in.  cream  bottles). 


samples  contain- 
ing less  than  one- 
tenth  per  cent, 
fat.  Some  of 
the  most  recent 
makes  of  turbine 
testers  are  pro- 
vided with  holes 
in  the  covers  and 
dampers.  A  ther- 
mometer is  also 
placed  in  the 
cover. 
Babcock  testers 


run  by  electricity  have  lately  been  put 
on  the   market  by   a   couple  of  manu- 
facturers   (fig.   23).     Where  no  steam, 
but  electrical  current  is  available,  these 
machines    may    be    in- 
stalled to  great  advan- 
tage, as  they  are  con- 
venient to  use  and  may 
be  depend*  d  on  to  run 
at  the  required  speed. 
Some  provision  for  get- 
ting hot  water  must  be 
at  hand  in  using  elec- 
trical Babcock  testers/ 


FIG.  25.  Type  of  Babcock  steam  turbine 
testers. 


1  The  method  of  installation  of  a  40-bottle  electrical  Babcock  tester 
is  described  in  detail  lit  Kept.  Dept.  of  Health,  City  of  Chicago,  1906 
p.  18. 


64  Testing  Milk  and  Its  Products. 

3.— SULFURIC  ACID. 

72.  The  sulfuric  acid  to  be  used  in  the  Babcoek  test 
should  have  a  specific  gravity  of  1.82-1.83.1  The  com- 
mercial sulfuric  acid  (sometimes  called  oil  of  vitriol) 
is  commonly  used ;  it  can  be  bought  for  about  2  cents  a 
pound  in  carboy  lots  and  25  cents  or  less  a  quart  at  re- 
tail. One  quart  of  acid  is  sufficient  for  fifty  tests.  The 
acid  should  be  kept  in  stoppered  glass  bottles,  prefer- 
ably glass  or  rubber  stoppered  ones,  since  a  cork  stop- 
per is  soon  dissolved  by  the  acid  and  rendered  useless. 
If  the  bottle  is  left  uncorked,  the  acid  will  absorb 
moisture  from  the  air  and  after  a  time  will  become  too 
weak  for  use  in  this  test. 

Lead  is  the  only  common  metal  which  is  not  dissolved 
by  strong  sulfuric  acid ;  where  considerable  milk  testing 
is  done,  it  is  therefore  desirable  to  provide  a  table  cov- 
ered with  sheet  lead  on  which  the  acid  may  be  handled. 
The  acid  dissolves  iron,  tin,  wood  and  cloth,  and 
burns  the  skin.  If  acid  is  accidently  spilled,  plenty  of 
water  should  be  used  at  once  to  wash  it  off.  Ashes, 
potash,  soda,  and  ammonia  neutralize  the  action  of  the 
acid,  and  a  weak  solution  of  any  one  of  these  alkalies 
can  be  used  after  the  acid  has  been  washed  off  with 
water.  The  red  color  caused  by  the  action  of  the  acid 
en  clothing  can  be  removed  by  wetting  the  spot  with 
weak  ammonia  water;  the  ammonia  must,  however,  bo 
applied  while  the  stain  is  fresh,  and  is  in  its  turn 
washed  off  with  water. 

1  A  specific  gravity  of  1.82  means  that  a  given  volume  of  the  arid 
weighs  1.82  times  as  much  as  the  same  volume  of  water  at  the  same 
temporal un-  (see  also  under  Lactometer,  109). 


The  Babcock  Test.  §5 

^ 

73.  Testing  the  strength  of  acid.     The  strength  of 
the  acid  can  be  easily  tested  by  the  use  of  a  balance  like 
that  shown  in  fig.  34  (91).    A  dry  test  bottle  is  weighed,^ 
and  then  filled  with  acid  exactly  to  the  zero  mark,  or 
to  any  ether  particular  line  of  the  scale.     It  is  then 
again  weighed  accurately;  the  difference  between  these 
two  weights  will  give  the  weight  of  the  acid  in  the  bot- 
tle.    The  bottle  is  then  emptied  and  rinsed  thoroughly 
with   water    (until  the   water   has  no   longer   an    acid 
taste)  ;  it  is  then  filled  with  water  to  the  same  line  as 
before  and  weighed;  the  difference  between  this  weight 
and  that  of  the  empty  bottle  gives  the  weight  of  the 
same  volume  of  water  as  that  of  the  acid  weighed.    The 
specific  gravity  of  the  acid  is  obtained  by  dividing  the 
weight  of  the  acid  by  the  weight  of  the  water.     If  the 
quotient  comes  between  1.82  and  1.83  the  strength  of 
the  acid  is  correct.    The  outside  of  the  test  bottle  should 
always  be  wiped  dry  before  the  liquids  are  weighed  in 
it.     Unless  great  care  is  taken  in  measuring  the  acid 
and  the  water,   and   in   weighing  both  these   and  the 
test  bottle,  the  results  obtained  will  not  be  trustworthy. 

74.  Acid  that  is  a  little  too  strong  can  be  used  by 
taking  less  than  the  required  amount  for  each  test,  e.  g., 
about  15  cc.     Operators  are  warned  against  reducing 
the  strength  of  the  acid  by  adding  water  to  it,  as  acci- 
dents may  easily  occur  when  this  is  done.    A  too  strong 
acid  can,  if  desired,  be  weakened  by  simply  leaving  the 
bottle  uncorked  for  a  time,  Or  by  pouring  the  acid  into 
a  bottle  containing  a  small  quantity  of  water.     In  the 
latter  case  the  first  portions  of  acid  should  be  added 
carefully,  a  little  at  a  time,  shaking  the  bottle  after 


66  Testing  Milk  and  Its  Products. 

each  addition,  so  as  not  to  cause  it  to  break  on  account 
of  the  heat  evolved  in  mixing  the  acid  and  the  water. 
Never  dilute  sulfuric  acid  by  pouring  water  into  it. 

A  helpful  suggestion  for  using  acid  that  is  too  strong 
or  would  give  a  charred  fat  on  account  of  high  tem- 
perature of  acid  or  milk,  or  both,  has  been  made  by  M. 
L.  Holm,  Assistant  Chemist  Chicago  Dept.  of  Health, 
viz.,  to  add  2  cc.  of  80  per  cent,  glycerin  (80  parts  of 
commercial  glycerin  and  20  parts  of  water,  by  volume) 
to  the  milk  sample,  prior  to  adding  the  acid.1  The  gly- 
cerin protects  the  milk  to  some  extent  from  the  acid  be- 
fore the  two  are  mixed,  and  a  clear  fat  may  thus  often 
be  secured  under  otherwise  unfavorable  conditions.  The 
results  appear  not  to  be  influenced  by  the  addition  of 
the  glycerin. 

75.  If  the  acid  is  a  little  too  weak,  correct  results 
may  be  obtained  by  using  more  than  the  specified  quan- 
tity, say  20  cc.  If  a  good  test  is  not  obtained  with  this 
quantity  of  acid,  a  new  lot  must  be  secured,  as  its  spe- 
cific gravity  in  such  a  case  is  below  1.82.  The  observing 
operator  will  soon  be  able  to  judge  of  the  strength  of 
the  acid  by  its  action  on  milk  in  mixing  the  two  liquids 
in  the  Babcock  test  bottles ;  it  is  indeed  remarkable 
•  what  slight  differences  in  the  specific  gravity  of  the 
acid  will  make  themselves  apparent  in  working  the  test, 
as  regards  the  rapidity  with  which  both  the  curdled 
milk  is  dissolved  and  the  mixture  of  acid  and  milk  turns 
black. 

1  American  Food  Journal,  1907,  No.  7,  p.  28;  Hoard's  Dairyman,  Nov. 
8,  1907. 


The  Babcock  Test.  67 

76.  Strength  of  sulfuric  acid.     The  relation  between 
the  strength  of  sulfuric  acid  and  its  specific  gravity 
will  be  seen  from  the  following  table: 

Specific  Gravity  of  Sulfuric  Acid  of  Different  Strength. 

Specific  Gravity  Sulfuric  Acid 

(1PC,  water  U°C).  (HZSOJ. 

1.841 97  per  cent. 

1.840 96 

1.839 95 

1.837 94 

1.834 93 

1.830 92 

1.825 91 

1.820 % 

1.815 89 

1.808 88 

It  will  be  noticed  that  the  sulfuric  acid  to  be  used  in 
the  Babcock  test  should  contain  90  to  92  per  cent,  of 
acid  (H2S04)  ;  slightly  weaker  or  stronger  acid  than 
this  may,  as  previously  stated,  be  used  by  varying  the 
quantity  of  acid  taken  for  each  test  according  to  the 
strength  of  the  acid,  but  successful  tests  cannot,  as  a 
rule,  be  made  with  acid  weaker  than  89  per  cent,  or 
stronger  than  95  per  cent. 

77.  The  Swedish  acid  tester  is  a  small  hydrometer,  intended 
to  show  whether  the  acid  used  in  the  Babcock  test  is  of  the  cor- 
rect strength.     An  examination  of   these   testers  will  show  that 
they  are  practically   useless  for  the  purpose  intended,  from  the 
fact  that  they   are   not    sufficiently    sensitive;    while    the    testers^ 
examined  were  found  to  sink  to  the  line  marked  Correct  on  the 
scale,  when  lowered   into   sulfuric  acid  of  a  specific   gravity  of 
1.83,  they   would  sink  to   a  point  much  nearer  the   same  mark, 
than  to  the  lines  marked   Too  strong  or  Too  weak,  respectively, 
when  lowered  into  either  too  strong  or  too  weak  acid. 

78.  The  color  of  the  fat  column  an  index  to  the 
strength  of  the  acid  used.  The  strength  of  the  acid 
is  indicated  to  a  certain  extent  by  the  color  of  the  fat 


68  Testing  Milk  and  Its  Products. 

which  separates  in  the  neck  of  the  test  bottle  when  milk 
is  tested.  If  the  directions  given  for  making  the  tests 
are  carefully  followed,  the  fat  separated  out  will  be  of 
a  golden  yellow  color.  If  the  fat  is  light  colored  or 
whitish,  it  generally  indicates  that  the  acid  is  too  weak, 
and  a  dark  colored  fat,  with  a  layer  of  black  material 
beneath  it,  shows  that  the  acid  is  too  strong,  provided 
the  temperature  of  both  milk  and  acid  is  about  70°. 
[For  influence  of  temperature,  see  next  paragraph.] 
The  acid  used  in  the  test  is  not  of  sufficient  strength 
to  appreciably  attack  the  fat  at  ordinary  temperatures 
of  testing,  but  a  variation  in  the  strength  of  the  acid 
or  in  the  temperature  of  the  milk  influences  the  in- 
tensity of  the  action  of  the  acid  on  the  fat,  as  shown  in 
the  color  of  the  fat  obtained. 

The  following  experiment  shows  the  relation  between 
the  strength  of  the  acid,  the  temperature  of  the  milk, 
and  the  color  of  the  fat: 

First: — From  a  sample  of  milk  measure  the  usual  quantity 
for  testing  into  each  of  three  bottles,  A,  B  and  C.  Place  A  in 
iced  water,  and  C  in  warm  water,  leaving  bottle  B  at  ordi- 
nary temperature.  After  the  bottles  have  been  left  for  ten  min- 
utes under  these  conditions,  add  the  normal  quantity  of  acid 
to  each  and  proceed  with  the  test  in  the  ordinary  manner. 

Second: — Measure  some  of  the  same  milk  into  three  other 
bottles,  D,  E  and  F.  Into  test  bottle  D  pour  the  usual  amount 
of  rather  weak  acid;  add  the  same  amount  of  acid  of  normal 
strength  (1.82-1.83)  to  bottle  E,  and  add  17.5  cc.  of  a  still 
stronger  acid  (concentrated  sulfuric  acid,  sp.  gr.  1.84),  in  test 
bottle  F;  complete  the  tests  in  the  usual  way. 

On  the  completion  of  the  preceding  six  tests  the  operator  will 
notice  that  the  fat  in  the  necks  of  test  bottles  A  (cold  milk) 
and  T>  (weak  acid)  is  much  lighter  colored  than  that  in  C  (warm 
milk)  and  F  (strong  acid),  and  that  tho  color  of  the  fat  in  B 
(normal  temperature)  and  E  (normal  acid)  is  somewhere  be- 
tween that  of  these  two  series. 


The  Babcock  Test.  69 

79.  Influence  of  temperature  on  the  separation  of 
fat.     The  intensity  of  the  action  of  the  sulfuric  acid 
on  the  milk  is  influenced  by  the  temperature  of  either 
liquid;  the  higher  the  temperature,   the  more   intense 
will  be  the  action  of  the  acid  on  the  solids  of  the  milk. 
It  may  be  noticed  that  acid  from  the  same  carboy  will 
act  differently  on  milk  in  summer  than  in  winter  time, 
if  the  acid  and  the  milk  are  not  brought  to  a  tempera- 
ture of  about  70°   before  testing  during  both  seasons. 
The  temperature  of  the  liquids  may  be  as  low  as  40°  F. 
in  winter  and  as  high  as  80°  F.  in  summer.     This  dif- 
ference of  forty  degrees  will   often  have   considerable 
influence  on»4he  clearness  of  the  fat  separated,  show- 
ing white  curdy  substances  and  a  light  colored  fat  in 
winter,  or  black  flocculent  specks,  with  a  dark  colored 
column  of  fat  in  summer.     Beth  these  defects  can  be 
avoided,  when  the  acid  is  of  the  proper  strength,  by 
bringing  the  temperature  of  the  milk  and  the  acid  to 
about  70°  F.  before  the  milk  is  tested. 

The  operator  should  be  particularly  cautious  against 
over-heating  either  milk  or  acid,  since  the  heat  intensi- 
fies the  action  of  the  acid  and  this  may  become  so  vio- 
lent as  to  force  the  hot  liquid  out  of  the  neck  of  the 
test  bottle  when  the  acid  is  added  to  the  milk,  thus 
spoiling  the  test  and  possibly  causing  an  accident. 

4.— WATER  TO  BE  USED  IN  THE  BABCOCK  TEST. 

80.  Eain  water,  condensed  steam,  or  soft  water  should 
be  used  for  the  purpose  of  bringing  the  fat  into  the 
neck  of-  the  test  bottles.    The  surface  of  the  fat  column 
will  then  usually  be'  clear  and  distinct.     The  foam  or 


70  Testing  Milk  and  Its  Products. 

bubbles  that  sometimes  obscure  the  upper  line  (menis- 
cus) of  the  fat,  making  indistinct  the  point  from  which 
to  measure  it,  is  generally  caused  by  the  action  of  the 
acid  on  the  carbonates  in  hard  water.  The  carbonic 
acid  gas  liberated  from  such  water  by  the  sulfuric  acid 
is  more  or  less  held  by  the  viscid  fat  and  produces  a 
layer  of  foam  on  its  surface.  If  clean  soft  water  cannot 
be  obtained  for  this  purpose,  hard  water  may  be  used,  by 
adding  a  few  drops  of  sulfuric  acid  to  the  water  before 
it  is  heated,  thus  causing  the  carbonic  acid  to  be  ex- 
pelled. By  simply  boiling,  many  hard  waters  will  be 
rendered  soft  and  adapted  to  use  in  the  Babcock  test, 
as  most  of  the  carbonates  which  cause  this  foaming  are 
thereby  precipitated. 

If  the  test  has  been  completed,  and  a  layer  of  foam 
appears  over  the  fat,  it  may  be  destroyed  by  adding  a 
drop  or  two  of  alcohol.  If  this  is  done,  the  fat  column 
should  be  read  at  once  after  the  alcohol  is  added,  as 
the  latter  will  soon  unite  with  the  fat  and  increase  its 
volume. 

81.  Reservoir  for  water.  When  only  a  few  tests  are 
made  at  one  time,  hot  water  can  be  added  with  the  17.6 
cc.  pipette.  If  many  tests  are  made,  the  water  is  more 
conveniently  and  quickly  filled  into  the  test  bottles  by 
drawing  it  from  a  small  copper  reservoir  or  tin  pail 
suspended  over  the  testing  machine.1  The  flow  of  water 
through  a  rubber  tube  connected  with  the  reservoir,  is 
regulated  by  means  of  a  pinch  cock.  The  water  must 
be  hot  when  added  to  the  test  bottles  so  as  to  keep  the 

1  Ordinary  tinware  will  soon  rust  when  water  is  left  standing  in 
it,  and  copper  reservoirs  are  therefore  more  economical. 


The  Babcock  Test. 


71 


t'at  in  a  melted  condition  until  the  readings  are  taken. 
Most  turbine  testers  are  now  made  with  a  very  conven- 
ient water  reservoir  attached  to  the  tester  (figs.  22-25). 
The  use  of  zinc  or  steel  oilers,  or  perfection  oil  cans 
has  been  suggested  as  a  handy  and  rapid  method  of 
adding  hot  water  to  the  test  bottles,  but  most  operators 
prefer  to  add  water  to  the  bottles  by  means  of  a 
piece  of  rubber  tubing  connected  with  a  reservoir,  as 
shown  in  the  illustrations  just  referred  to. 

5. — MODIFICATIONS  OF  THE  BABCOCK  TEST. 

82.  The  Russian  milk  test.  The  same  chemical  and  me- 
chanical principles  applied  in  the  regular  Babcock  test,  are  used 
in  the  Russian  milk 
test,  except  that  in 
this  case  the  machine 
in  which  the  bottles 
are  whirled,  and  the 
bottles  themselves,  are 
so  constructed  that 
the  latter  can  be  filled 
with  hot  water  while 
the  machine  is  run- 
ning, thus  saving 
time  and  the  trouble 
incident  to  the  stop- 
ping of  the  tester  and 
filling  the  bottles  by  means  of  a  pipette.  The  milk-measuring 
pipette  (fig.  28)  and  the  acid  measure  used  in  the  Eussian  test 
are  one-half  of  the  ordinary  size,  and  the  test  bottles  are  made 
in  two  pieces  with  a  detachable  narrow  graduated  stem  (see  fig. 
27).  The  machine  is  substantially  made  of  cast  iron;  it  is  pro- 
vided with  a  very  satisfactory  speed  indicator  which  shows  at 
any  time  the  number  of  revolutions  at  which  the  bottles  are 
being  turned.  The  accompanying  illustrations  show  the  appa- 


FIG.  26.    The  Russian  test. 


72 


Testing  Milk  and  Its  Products. 


ratus  used  in  this  test.  When  the  directions  for  operating,  the 
test  are  followed  closely,  the  results  obtained  are  accurate  and 
very  satisfactory 

83.  Barllett's  modification.      Bartlett1    proposed    a    modifi- 
cation  of   the   method   of   procedure   in   the   Babcock   test,   which 

aims  to  simplify  the  manipulations.  20 
cc.  of  acid  are  added,  instead  of  17.5 
cc.,  and  the  bottles  filled  with  the  milk- 
acid  mixture  are  left  standing  for  not 
less  than  five  minutes  and  then  filled 
with  hot  water  to  within  the  scale;  the 
bottles  are  then  whirled  for  five  min- 
utes at  the  regular  rate  (52). 

83a  Siegfeld's  modification.  The 
German  dairy  chemist  Siegfeld  in 
1899  proposed  a  modification  of  the 
Babcock  test  (MolTcerei  Ztg.  1899,  p. 

O51)  using  2  cc.  of  amyl  alcohol  with 
the  sulfuric  acid,  and  filling  up  with 
dilute  sulfuric  acid  (1:1,  sp.  gr.  1.5) 

in   one   filling,    in   place   of   water   after 

the  whirling.     A  clear  separation  of  the 
fat  is  facilitated  by  both  these  changes, 
but    when    properly    conducted    there    is 
no    difficulty    whatever    in    obtaining    a 
clear  fat  column  in  the  Babcock  test  as  Pipette  used 
described  in  this  book,  and  the  modifica-  ^an^es/^'^ 
tion  will   not   therefore   be   likely   to   be 
FIG.  27.       generally  introduced  in  American  factories.     It  has, 
used8  in   the  however,  been   adopted   in    many   German   creameries 
Russian  test.  where   the   Babcock   test   is  used. 

84.  Bausch  and  Lomb  centrifuge.    Fig.  29  shows  a  form  of 
hand  centrifuge  which  may  be  used  to  advantage  by   physicians 
of   in   pathological   laboratories   for   the   determination   of   fat  in 
milk.     The  centrifuge  is  especially  designed   for  examination  of 
urine,  sputum,  blood,  etc.,  but  has  been  adapted  to  milk  analysis 
by  the  Leflfmann  &  Beam  test,  a  special  form  of  bottle   (fig.  30) 


X 


FIG.  28. 


Maine  experiment  station,  bull.  81  (H.  *.). 


The  Babcock  Test. 


73 


having  been  constructed  for  this 
purpose.  The  machine  gives  satis- 
factory results  by  the  Babcock  test 
as  well,  provided  the  acid  used  is 
1.83-1.84,  or  if  the  bottles  contain- 
ing the  acid-milk  mixture  be  placed 
in  hot  water  for  five  or  ten  minutes 
prior  to  the  whirling.  As  the  bottles 
are  calibrated  for  only  5  cc.  of  milk 
and  the  neck  of  the 
bottles,  with  scale,  is 
correspondingly  fine, 
testing  milk  with  this 
machine  requires  some 
nicety  of  manipula- 
tion not  called  for  in 
case  of  regular  Bab- 
cock testers  constructed 


FIG.  29.    Physician's  centri-    for  the  use   of   farmers  f^t  tJhvsi- 

ir»Q    +Ko+    1^0  IT    Via  11  ttrtsl     tr\ ,'  ™  <  I  IT  .  V.  J 


FIG.  30. 
Test  bottle 
pipette 


fuge  that  may  be  used  for  milk 
testing. 


and   dairymen. 


clan's    cen- 
trifuge. 


Questions. 

1.  Give  a  short  description  of  the  Babcock  test. 

2.  State  precautions  to  be  observed  in  each  of  the  following 
operations:      (a)    Measuring  the  milk,    (b)    adding  the  acid,    (c) 
whirling  the  bottles,  (d)  adding  the  water,  (e)  measuring  the  fat. 
If    the   fat   separates   clear,   but   the   results   come   evidently    too 
low,  what  is  the  probable  cause,  and  how  can  the  correct  test  be 
established? 

3.  To    what   extent    does    the    temperature    of    the    fat,    when 
read,  influence  the  result? 

4.  Explain  the  graduations  of  the  milk  test  bottle. 

5.  What  is  the  capacity  of  the  neck  of  a  milk  test  bottle  be- 
tween the  0  and  10  marks,  expressed  in  cc.,  and  in  grams? 

6.  If  the   graduations   of   a  test  bottle  measure  2.3   cc.   from 
0  to  10%,  what  would  be  the  correct  test  of  a  sample  which  reads 
3.4%   fat   in   this   bottle? 


74  Testing  MUk  and  Its  Products. 

7.  Describe   three  different   methods  of   calibrating  milk   test 
bottles. 

8.  Describe    the    proper    construction    of    the    milk-measuring 
pipette;    what   weight   of  milk   does  it   deliver? 

9.  What  is  a  Swedish  acid-bottle? 

10.  What  speed  is  required  for   testers  having   a  diameter  of 
8,  15,  and  20  inches? 

11.  Write  an  order  for  one  gallon  of  sulfuric  acid  to  be  used 
in  testing. 

12.  How  can  the  strength  of  the  acid  be  tested  at  the  farm  or 
in  a  factory? 

13.  State    precautions   to   be   taken    in   using   an    acid   that    is 
(a)    too  strong,   (b)   too  weak. 

14.  What  may  the  color  of  the  fat  indicate  in  regard  to  the 
strength  of  the  acid  or  temperature  of  either  acid  or  milk? 

15.  What  is  the  cause  of  foam  above  the  fat  column,  and  how 
may   it  be  prevented? 

16.  What  causes  white  curd  or  black  specks  in  the  fat? 

17.  Describe  a  few  modifications  of  the  Babcock  test. 

18.  In    which    two    points    does    the   Eussian   milk    test   mainly 
differ  from  the  Babcock  test? 


CHAPTER  IV. 
CREAM  TESTING. 

85.  Cream  may  be  tested  by  the  Babcock  test  in  the 
same  manner  as  milk,  and  the  results  obtained  are  ac- 
curate when  the  necessary  care  has  been  taken  in  sam- 
pling the  cream  and  measuring  the  fat.  The  composi- 
tion of  cream  varies  greatly  according  to  the  process  of 
creaming,  the  temperature  of  the  milk  during  the  cream- 
ing, the  quality  and  the  composition  of  the  milk,  etc. 
The  cream  met  with  in  separator  creameries  will  con- 
tain from  25  to  40  per  cent,  of  fat,  or  on  the  average 
about  35  per  cent.  Cream  from  hand  separators  may 
be  as  rich  as  this,  but  it  often  contains  only  20  per  cent. 


FIG.  31. 
Students  testing  dairy  products 


76  Testing  Milk  and  Its  Products. 

of  fat  as  delivered  to  creameries.  An  average  grade  of 
market  cream  as  retailed  contains  about  25  per  cent,  of 
fat.  If  18  grams  of  25  per  cent,  cream  is  measured 
into  an  ordinary  Babcock  test  bottle,  there  will  be 
18  X -25=4.5  grams  of  pure  butter  fat  in  the  bottle, 
or,  (since  the  specific  gravity  of  butter  fat  is  about  .9) 
i^  =  5  cc.  It  is  shown  that  the  space  from  0  to  10 
in  the  neck  of  these  bottles  holds  exactly  2  cc.  (44). 
The  neck  of  the  milk  test  bottle  is  not  large  enough  to 
show  the  per  cent,  of  fat  in  a  sample  of  cream  if  18 
grams  are  taken  for  testing,  and  it  is  therefore  neces- 
sary to  adopt  special  measures  when  cream  is  to  be 
tested. 

86.  Errors  of  measuring  cream.  Several  factors 
tend  to  render  inaccurate  the  measuring  of  cream  for 
the  Babcock  test,  and  correct  results  can  therefore  only 
be  obtained  by  weighing  the  cream.  If  a  17.6  cc.  pi- 
pette is  used  in  testing  the  cream,  it  will  not  deliver 
18  grams  of  crgam,  as  it  will  of  milk,  for  the  following 
reasons : 

1.  The  specific  gravity  of  cream  is  lower  than  that  of 
milk;  if  a  certain  quantity  of  milk  weighs  1030  Ibs.,  the 
same  quantity  of  cream  will  weigh  from  1020  Ibs.  to 
1000  Ibs.  or  less,  the  weight  being  determined  by  the 
richness  of  the  cream ;  the  more  fat  the  cream  contains, 
the  less  a  certain  quantity  of  it,  e.   g.,  a  gallon,  will 
weigh.1 

2.  Cream  is  thicker  (more  viscous)   than  milk  at  the 
same  temperature,   and  more  of  it  will  adhere  to  the 
sides  of  the  measuring  pipette  than  in  the  case  of  milk. 

*  For  specific  gravity  of  cn-niii  of  ditTm-nt  richness,  s«-.-  tsiblron  p. 77. 


Cream   Testing.  11 

This  is  of  special  importance  in  testing  very  rich  or 
sour  cream. 

3.  In  case  of  separator  cream,  more  or  less  air  will 
become  incorporated  with  the  cream  during  the  process 
of  separation.  In  the  ripening  of  cream,  the  fermenta- 
tion gases  developed  are  held  in  the  cream  in  the  same 
way  as  bread  dough  holds  the  gases  generated  by  yeast. 
In  either  case  the  weight  of  a  certain  measure  of  cream 
is  diminished. 

87.  As  an  illustration  of  the  effect  of  the  preceding 
factors  on  the  amount  of  cream  measured  out  by  a  Bab- 
cock  17.6  cc.  pipette,  the  following  weighings  of  sepa- 
rator cream  are  given  (column  b.)  Tha  cream  was  in 
all  cases  fresh  from  the  separator;  it  was  weighed  as 
delivered  by  the  pipette  into  a  cream  test  bottle  (89), 
and  the  test  proceeded  with  at  once ;  the  specific  gravity 
of  the  cream  was  determined  by  means  of  a  picnometer 
(248).  The  data  given  are  in  all  cases  averages  of  sev- 
eral determinations;  the  samples  of  ci^am  have  been 
grouped  according  to  their  average  fat  contents.1 

Weight  of  fresh  separator  cream  delivered  by  a  17.6  cc.  pipette. 


Per  cent 
of  fat 
in  cream. 

Specific  gravity  (  17.5°C.  } 
(a) 

Weight  of  cream  deliv- 
ered, grams, 
(b) 

10 

1.023 

17.9 

15 

1.012 

17.7 

20 

1.008 

17.3 

25 

1.002 

17.2 

30 

.996 

17.0 

35 

.980 

16.4 

40 

.966 

16.3 

45 

.950 

16.2 

50 

.947 

15.8 

1  For  Influence  of  condition  of  cream  on  the  amount  measured  out 
with  a  17.6  cc.  pipette,  see  also  Bartlett,  Maine  exp.  sta.,  bull.  31  (S. 
S.);  Jones,  Vt.  exp.  sta.,  report  16,  101-6,  and  "Dean,  Guelph  (Ont.)  agr. 
college,  report  1906,  p.  125. 


78  Testing  Milk  and  Its  Products. 

The  figures  in  the  table  show  plainly  the  variations 
in  the  specific  gravity  of  cream  of  different  richness 
and  the  error  of  making  tests  of  cream  by  measuring  it 
with  a  17.6  cc.  pipette,  especially  if  the  pipette  is  not 
rinsed  and  the  washings  added  to  the  test  bottle ;  if  the 
cream  to  be  sampled  is  fresh  separator  cream  testing 
over  30  per  cent.,  less  than  17.0  grams  of  cream  will  be 
delivered  into  the  test  bottle,  and  the  results  of  the 
reading  will  be  at  least  one-eighteenth  too  low  (since 
the  bottles  are  graduated  for  18  grams),  or  about  1.6 
per  cent,  too  low  in  the  case  of  a  30  per  cent,  cream.  If 
the  cream  is  sour,  the  error  will  of  course  be  still  greater. 

It  should  be  remembered  that  the  specific  gravities 
of  the  cream  given  in  the  table  refer  to  fresh  separator 
cream  only.  Considerable  air  is  incorporated  during 
the  separation,  and  cream  of  this  kind  is  therefore  lighter 
than  gravity  cream  of  corresponding  fat  contents. 

88.  Weighing  cream  for  testing.  For  the  reasons 
stated  in  the  preceding,  accurate  tests  of  cream  can 
only  be  made  by  weighing  the  cream  into  the  Babcock 
test  bottles.1 

The  simplest  method  is  to  weigh  9  or  18  grams  of  the 
sample  on  a  small  cream-weighing  scale  (see  p.  80)  into 
one  of  the  special  forms  of  cream-test  bottles. 

Cream-test  bottles.  Special  forms  of  bottles  have 
been  devised  for  testing  samples  of  cream  by  the  Bab- 
cock  test  by  Winton,  Bartlett,  and  by  various  manu- 
facturers. 

1  This  is  recognized  by  a  law  passed  by  the  Wisconsin  legislature  of 
1903,  which  requires  cream  to  be  weighed  for  testing  where  it  is  sold  on 
the  basis  of  its  fat  content.  (Chapter  43,  laws  of  1903,  An  act  to  pre- 
scribe the  standard  measures  for  the  use  of  the  Babcock  test  in  deter- 
mining the  per  cent,  of  butter  fat  in  milk  or  cream.) 


Cream  Testing.  79 

89.  The  Winton  cream  bottle.     The  cream-test  bot- 
tle devised  by  "Winton,1    (fig.  32),  has  a  neck  of  the 
usual  length,  and  of  sufficient  width  to  measure  30  per 
cent,  of  fat.    The  scale  of  the  neck  is  divided 

into  parts  representing  one-half  of  one  per 
cent,  each,  but  readings  of  a  quarter  of  a  per 
cent,  can  easily  be  estimated.  Such  readings 
of  cream  tests  are  sufficiently  exact  for  most 
commercial  purposes,  e.  g.,  in  creameries. 
This  form  of  cream  bottle  will  be  found  very 
convenient  in  making  tests  of  composite  sam- 
ples of  cream. 

Cream  test  bottles  of  a  small  bore  are 
greatly  to  be  preferred  to  those  with  wide 
necks  (fig.  32),  since  they  permit  of  accurate 
readings  to  a  quarter  of  a  per  cent. 

Other    forms   of   cream-test   bottles   which 

will  allow  the  testing  of  50  or  55  per  cent. 

FIG  32. 
cream  have  been  placed  on  the  market  dur-  Thewinton 

ing  late  years  by  some  manufacturers.  These  bottiem 
bottles  (so-called  9-inch  bottles]  have  long  necks  and 
require  especially  constructed,  large  and  deep  testers 
(see  fig.  25).  These  machines  and  accompanying  bot- 
tles have  of  late  been  adopted  for  cream  testing  in 
many  localities  where  farm  separator  cream  is  deliv- 
ered to  the  creameries. 

90.  The  bulb-necked  cream  bottles   (fig.  33)   allow  the  test- 
ing of  cream   containing  23    or   25   per   cent,   of  fat,  when   the 
usual    quantity    of    cream    (18    grams)    is    taken.      The    neck    is 
graduated  from  0  to  23  per  cent.,  and  in  some  cases  to  25  per 

i  Connecticut  experiment   station  (New  Haven),  bull.    117;  report 
1894,  p.  224. 


•80 


Testing  Milk  and  Its  Products. 


cent.,  the  graduation  extending  both  below  and  above  the  bulb. 
This  is  sometimes  an  inconvenience,  as  the  water  must  be  added 
carefully  so  that  the  lower  end  of  the  column  of  fat  will  always 
come  below  the  bulb,  in  the  graduated  part  of  the  neck,  and 
not  in  the  bulb  itself.  Beginners  are  especially  apt  to  lose  tests 
when  this  bottle  is  first  used,  for  the  reason  given.  It  is  rec- 
ommended to  fill  these  bottles  with  the  first  portion 
of  hot  water  to  just  above  the  bulb,  so  that  one 
can  see  how  much  water  to  add  the  second  time  in 
order  to  bring  the  fat  within  the  scale. 

Each  division  of  the  scale  on  these  cream  bottles 
represents  two-tenths  of  one  per  cent,  of  fat,  as 
in  case  of  the  milk  test  bottles.  This  form  of  bot- 
tle is  no  longer  used  to  any  extent,  as  it  has  been 
largely  replaced  by  the  Winton  cream-bottle. 

91.  Scales  for  weighing  the  cream.  When 
a  small,  delicate  balance  is  used,  cream  can 
be  weighed  rapidly  into  the  bottles.  Either 
of  the  scales  shown  in  the  accompanying  il- 
lustrations, (figs.  34-35),  will  be  found  suf- 
ficiently accurate  for  this  purpose;  a  small 
scale  of  this  kind  is  also  convenient  and  help- 
ful in  testing  cheese,  butter  and  condensed 
milk,  in  determining  the  strength  of  sulfuric 
acid,  and  in  testing  the  accuracy  cf  test  bot- 
tles and  pipettes.  In  testing  cream  by 
FIG.  38.  . 

The  bulb- weight,  the  test  bottle  is  first  weighed  empty, 

necked  cream  .  „  , 

test  bottle,  and  again  when  9  or  18  grams  01  cream  have 
been  placed  in  it;  the  difference  between  the  two  weights 
gives  the  weight  of  cream  taken  for  the  test.  If  the 
cream  contains  less  than  30  per  cent,  of  fat,  the  regu- 
lar milk  test  bottle  can  be  used  for  testing  the  cream,  if 
not  much  more  than  5  grams  are  weighed  out ;  if  more 
cream  is  taken,  or  if  this  is  richer  than  30  per  cent.,  it 
is  advisable  to  use  cream  bottles. 


Cream   Testing. 


81 


The  cream  scale  shown  in  fig.  34  permits  the  weighing 
of  six  samples  of  cream  on  each  pan  with  only  one  tar- 

ing of  the  bottles,  which 
greatly  facilitates  the 
work  of  testing  the 
cream. 

The  operator  should  be 
careful   in   weighing  the 

FIG.  34.     Scales  used  for  weighing    Cream    not    to    Spill    it    On 
cream,  cheese,  etc.,  In  the  Babcock     ,,  ,    .  -.  /,     ,, 

test.  the    outside    01    the    test 

bottle.   If  less  than  18  grams  of  cream  has  been  weighed 

into  the  bottle,  sufficient  water  is  added  to  the  bottle 

to  make  the  total  volume  about  18  cc.     The  usual  quan- 

tity of  acid  (17.5  cc.)  is  then  added,  and  the  test  com- 

pleted   in    the    ordinary 

manner.     The  reading  of 

the  amount  of  fat  in  the 

neck    of   the    test   bottle 

will  not  show  the  correct 

per   cent,    of   fat   in   the 

cream    unless  exactly    18 

grams    are    weighed    out. 

If  less  than  this   weight 

was    taken    the    per    cent, 

oi  rat  in  the  cream  tested 

is  obtained  by  multiplying  the  reading  by  18,  and  di- 

viding the  product  by  the  weight  cf  cream  taken. 

EXAMPLE:     Weight  of  cream  tested,  5.2  grams;  reading  of  col- 
umn of  fat  ^O.S,  2)9.7,  average  9.75;  per  cent,  of  fat  in  the  cream 


FIG.  35.  Torsion  balance  used  for 
weighing  cream,  butter,  cheese,  etc., 
in  the  Babcock  test.  Sensitive  to  .01 


9.75X18 
*  5.2 


=33.75. 


82  Testing  Milk  and  Its  Products. 

It  is  very  convenient  to  weigh  out  18  grams  of  cream 
(or  a  fraction  thereof)  so  that  the  readings  may  be 
taken  directly  from  the  neck  of  the  bottle.  The  smaller 
the  quantity  of  cream  taken  for  a  sample,  the  greater 
is  the  error  introduced  by  inaccurate  weighings  or  read- 
ings. The  result  is  rendered  more  accurate  and  certain 
if  two  or  three  tests  of  a  sample  are  made,  and  the 
readings  averaged. 

92.  Measuring  cream  for  testing.  Where  a  special 
cream  scale  or  a  small  balance  is  not  available,  fairly 
satisfactory  results  may  be  obtained  with  cream  of  low 
or  average  quality  by  measuring  out  the  sample  with 
a  17.6  pipette  and  correcting  the  results  as  indicated 
below.  One  cf  the  cream  test  bottles  or  a  common  milk 
test  bottle  may  be  used  for  this  purpose.  The  table 
on  p.  76  shews  that  a  17.6  cc.  pipette,  in  the  case  of 
cream  fresh  from  the  separator,  containing  less  than 
25  per  cent,  of  fat,  will  deliver  only  17.2  grams  of 
cream,  that  is,  the  results  will  bei**i5=l.l  per  cent,  too 
low.  In  the  same  way  in  case  of  40  per  cent,  cream, 
only  16.3  grams  of  cream  would  be  delivered,  and  the 
results  therefore  3.8  per  cent,  too  low.  When  the  cream 
has  been  ripened  or  is  thick,  less  cream  would  be  deliv- 
ered than  the  amounts  given,  and  the  error  introduced 
by  measuring  out  the  samples  correspondingly  increased. 
A  table  of  correction  for  testing  such  cream  by  meas- 
uring the  samples  has  been  prepared  by  Prof.  Eckles, 
formerly  of  Iowa  experiment  station.1 

1  Press  bull,  dated  August,  1901.     Bonn1  croMim»rit>s   boat   tin-  sam- 
ples of  en-am  in  a  w:il«-r  bath  to  about  110°  K.  brforo  tin-  test    -;mipl«-s 


Cream  Testing.  83 

Approximately  correct  results  may  be  obtained  in 
testing  thin  cream  by  using  an  18  cc.  measuring  pipette ; 
to  avoid  the 'expense  and  trouble  of  using  two  different 
pipettes,  one  for  milk  and  one  for  cream,  a  pipette  with 
two  marks  on  the  stem,  at  17.6  cc.  and  18  cc.,  has  been 
placed  on  the  market,  the  former  mark  being  used  when 
milk  is  tested,  and  the  latter  for  cream.  It  should  be 
borne  in  mind,  however,  that  such  pipettes  can  only  be 
used  with  fairly  satisfactiry  results  in  the  case  of  sweet 
cream  of  average  richness. 

93.  Use  of  milk  test  bottles.  Cream  may  be  tested 
by  emptying  a  17.6  cc.  pipetteful  of  the  sample  into 
two  or  more  milk  test  bottles,  dividing  the  amount  about 
equally  between  the  bottles  and  filling  the  pipette  with 
water  once  or  twice,  which  is  then  in  turn  divided  about 
equally  between  the  test  bottles ;  the  per  cent,  of  fat  in 
the  cream  is  found  by  adding  the  readings  obtained  in 
each  of  the  bottles.  The  cream  and  the  water  must  be 
mixed  "before  the  acid  is  added. 

This  method  does  away  with  the  error  incident  to  the 
adhesion  of  cream  to  the  side  of  the  pipette,  but  not 
with  that  due  to  the  low  specific  gravity  of  the  cream, 
and  the  results  obtained  will  therefore  be  too  low.  The 


are  measured  out  by  means  of  a  17.6  cc.  pipette.  This  increases  the  fluid- 
ity of  the  cream  and  causes  less  to  adhere  to  the  pipette.  The  Vermont 
experiment  station  found  in  examining  this  method  that  it  did  not 
yield  satisfactory  results  in  the  case  of  cream  of  different  richness 
and  recommends  that  cream  be  weighed  when  accurate  tests  are  de- 
sired. (See  report  16,  pp.  191-6.) 

Professor  Spillman,  in  Bull.  32  of  Washington  experimentlstation, 
recommends  the  use  of  a  17.6  cc.  pipette  for  testing  cream,  the  results, 
obtained  being  corrected  by  a  certain  per  cent.,  as  showrn  in  a  table 
given  in  the  bulletin.  The  table  is  based  on  the  figures  given  on  p.  77 
of  this  book,  and  is  therefore  only  applicable  to' fresh  separator  cream. 


84  Testing  Milk  and  Its  Products. 

dilution  of  the  cream  with  water  in  the  test  bottles  not 
only  makes  it  possible  to  bring  into  the  bottle  all  the 
cream  measured  out,  but  also  insures  a  clear  test.  If 
ordinary  cream  is  mixed  with  the  usual  quantity 
of  sulfuric  acid  used  in  the  Babcock  test,  a  dark-colored 
fat  will  generally  be  obtained,  while  the  cream  diluted 
with  an  equal  or  twice  its  volume  of  water,  when  mixed 
with  the  ordinary  amount  of  acid,  will  give  a  light  yel- 
low, clear  column  of  fat,  which  will  allow  of  a  very- 
distinct  and  sharp  reading. 

The  number  of  bottles  to  be  used  for  testing  a  sam- 
ple of  cream  by  this  method  must  be  regulated  by  the 
richness  of  the  cream.  If  the  sample  probably  contains 
20  per  cent,  or  more,  a  pipetteful  should  be  divided 
nearly  equally  between  three  milk  test  bottles,  and  two- 
thirds  of  a  pipetteful  of  water  is  added  to  each  bottle. 
If  the  cream  contains  less  than  20  per  cent,  of  fat,  it 
will  only  be  necessary1  to  use  two  milk  test  bottles,  divid- 
ing the  pipetteful  between  these,  and  adding  one-half 
of  a  pipetteful  of  water  to  each  bottle. 

By  using  cream  test  bottles  (89),  more  accurate  tests 
may  be  obtained  in  case  of  cream  containing  as  much 
as  25  per  cent,  of  fat,  by  dividing  one  pipetteful  be- 
tween two  bottles,  rinsing  half  a  pipette  of  water  into 
each  one,  than  by  adding  all  the  cream  to  one  bottle 
without  rinsing  the  pipette,  for  reasons  apparent  from 
what  has  been  said  in  the  preceding. 

94.  Use  of  a  5  cc.  pipette.  When  the  cream  is  in  good  con. 
dition  for  sampling,  satisfactory  results  can  also  be  obtained  by 
the  use  of  a  5  cc.  pipette,  provided  great  care  is  taken  in  mix- 
ing the  cream  before  sampling;  5  cc.  of  cream  are  measured  into 


Cream  Testing. 


85 


-d, 


a  milk  test  bottle,  and  two  pipettefuls  of  water  are  added.  In 
this  way  all  the  cream  in  the  pipette  is  easily  rinsed  into  the 
test  bottle.  The  readings  multiplied  by  ^=3.6  will  give  the 
per  cent,  of  fat  in  the  cream.  If  the  specific  gravity  of  the 
cream  tested  varies  appreciably  from  1,  corrections  should  be 
made  accordingly;  e.  g.,  if  the  specific  gravity  is  1.02,  the  fac- 
tor should  read  .^  —3.53;  if  .95,  -Ji^.  =3.79,  etc. 

95.  Proper  readings  of  cream  tests.  The  accom- 
panying illustration  (fig.  36),  shows  the  proper  method 
of  reading  the  fat  column  in  cream 
tests;  readings  are  taken  from  a  to  c, 
not  to  &  or  to  d,  when  readings  are 
made  at  140°  P.1 

No  special  precautions  other  than 
those  required  in  testing  milk  have  been 
found  necessary  in  testing  cream,  ex- 
cept that  it  is  sometimes  advisable  not 
to  whirl  the  test  bottles  in  the  centri- 
fuge at  once  after  mixing,  but  to  let  the 
cream-acid  mixture  stand  for  a  while, 
until  it  turns  dark  colored.  At  first, 
the  mixture  of  cream  and  acid  is  much 
lighter  colored  than  that  of  milk  and 
acid,  owing  to  the  smaller  proportion  of 

FIG.  36.    Measur- 

n  solids  not  fat  contained  in  the  cream. 

The  liquid  beneath  the  fat  in  a  com- 
pleted test  of  cream  is  sometimes  milky 
and  the  fat  appears  white  and  cloudy,  making  an  exact 


ins  the6 

cream  bottle.  Read- 
ing should  be  made 
from  a  to  c,  not  to  b 
or  to  d. 


1  The  size  of  the  meniscus  is  magnified  in  this  cut.  A  study  of  the 
meniscus  formed  in  bottles  with  narrow  or  wide  necks,  and  its  bearing 
on  the  results  of  cream  tests  is  given  in  bulletin  58,  Bur.  An.  Ind., 
U.  S.  Dept.  of  Agriculture,  where  a  discussion  of  the  influence  of  dif- 
ferent temperatures  on  readings  of  cream  tests  will  also  be  found 
(see  96). 


86  Testing  Milk  and  Its  Products. 

reading  difficult.  Such  defects  can  usually  be  over- 
come by  placing  the  test  bottles  in  hot  water  for  about 
ten  minutes  previous  to  the  whirling,  or  by  allowing  the 
fat  to  crystallize  (which  is  done  by  cooling  the  bottles 
in  cold  water  after  the  last  whirling)  and  remelting 
it  by  placing  the  bottles  in  hot  water. 

The  error  due  to  the  expansion  of  the  fat  in  case  of 
excessively  hot  turbine  testers  having  no  openings  in 
the  cover  as  mentioned  on  p.  36,  is  especially  noticeable 
in  cream  testing,  where  it  may  amount  to  one  per  cent, 
or  more.  In  order  to  obtain  correct  results  with  such 
testers,  the  hot  cream  test  bottles  must  be  placed  in 
water  at  about  140°  F.  for  some  minutes  before  the 
results  are  read  off. 

96.  The  subject  of  different  methods  of  reading 
cream  tests  has  been  studied  by  Webster  and  Gray/ 
who  conclude  that  correct  results  are  obtained  by 
taking  readings  at  120°  F.,  from  the  bottom  to  the  ex- 
treme top  of  the  fat  column,  deducting  four-fifths  of 
the  depth  of  the  meniscus  from  this  result  and  adding 
.2  per  cent,  to  the  figure  thus  obtained.  The  error  due 
to  differences  in  the  diameter  of  the  necks  of  the  test 
bottles  is  thus  done  away  with.  In  the  case  of  tests  of 
9-gram  samples,  the  reading  is  doubled  before  .2  per 
cent,  is  added.  While  this  method  of  reading  does 
away  with  the  error  "due  to  the  varying  depths  of  the 
meniscus  in  bottles  with  narrow  and  wide  necks,  it  re- 
fers to  reading  the  tests  at  a  lower  temperature  than 
is  now  generally  practiced  in  factories,  viz.,  at  120°,  in- 

1  Bull.  58,  Bur.  An.  Ind.,  U.  S.  Dept.  of  Agriculture. 


Cream   Testing.  87 

stead  of  140°  (see  41).  Pending  a  similar  investiga- 
tion as  that  referred  to  above,  for  a  temperature  of 
140°,  it  is  well  to  read  cream  tests  to  the  bottom  of  the 
meniscus  (at  c,  fig.  36)  at  this  temperature,  rather  than 
to  5  or  d,  as  it  is  believed  that  more  correct  results  will 
be  obtained  by  this  method  of  reading. 


1.  Give   three  reasons  for  weighing  cream   for   testing. 

2.  How  does  the  richness  of  the   cream  influence  its  weight? 

3.  What  will  be  the   weight  of   one   gallon   of    cream   testing 
10,  30,  or  50%  fat? 

4.  Describe   at  least  three  forms  of   cream  test  bottles. 

5.  What  is  the  use  of  a  bulb  in  the  cream  bottle. 

6.  Between  what  points  should  the  cream  fat  column  be  read? 

7.  If  cream  was  erroneously  weighed  into  a  test  bottle  as  9.3 
gr.  instead  of  10  gr.,  what  error  would  this  cause  on  a  sample 
testing    33%    fat? 

8.  Mention   a  few  important  points  in   the  construction   of  a 
cream  test  bottle. 

9.  If  12.5  gr.  cream  give  a  reading  of  18.5,  what  is  the  cor- 
rect test  of  the  sample? 

10.  If  7.2  gr.  of  cream  give  a  reading  of  6.4,  what  is  the  cor- 
rect test  of  the  sample? 

11.  If  the  fat  in  a  cream  test  is  read  as  28%  at  a  temperature 
of  180°  P.,  what  is  the  correct  test? 

12.  If  at  the  end  of  a  full  day's  run  4,280  Ibs.   of  milk  had 
been  received,  testing  3.95  per  cent.,  and  535  Ibs.  of  cream  test- 
ing 34.5  per  cent,   fat;   how  much   fat    (a)    in   the  whole  milk; 
(b)    in   the  cream;    (c)    in   the   skim   milk?    (d)    what  would  be 
the  test  of  the  skim  milk,    (e)   how  many  pounds  of  skim  milk 
would  there  be;  and  (f)   what  would  be  the  per  cent,  of  cream 
from  the  milk? 


CHAPTER  V. 
BABCOCK  TEST  FOR  OTHER  MILK  PRODUCTS. 

97.  Skim  milk.  Each  division  on  the  scale  of  the 
neck  of  the  regular  Babcock  test  bottle  represents  two- 
tenths  of  one  per  cent.  (44).  When  a  sample  of  skim 
milk  or  butter  milk  containing  less  than  this  per  cent, 
of  fat  is  tested,  the  estimated  amount  is  expressed  by 
different  operators  as  one-tenth,  a  trace,  one-tenth  trace, 
or  one-  to  five-hundredths  of  one  per  cent.  Gravimetric 
chemical  analyses  of  skim  milk  have,  however,  shown 
that  samples  which  give  only  a  few  small  drops  of  fat 
floating  on  the  water  in  the  neck  of  the  test  bottle,  or 
adhering  to  the  side  of  the  neck,  generally  contain 
one-tenth  of  one  per  cent,  of  fat,  and  often  more.  Sam- 
ples of  skim  milk  containing  less  than  one-tenth  of  one 
per  cent,  of  fat  are  very  rare,  and  it  is  doubtful  whether 
a  sample  of  separator  skim  milk  representing  a  run 
of,  say  5000  Ibs.  of  milk,  has  ever  shown  less  than 
five-hundredths  of  one  per  cent,  of  fat.  Under  ordi- 
nary factory  conditions,  few  separators  will  deliver 
skim  milk  containing  under  one-tenth  of  one  per  cent, 
of  fat,  when  the  sample  is  taken  from  the  whole  day's 
run.  This  must  be  considered  a  most  satisfactory  sepa- 
ration.1 

1  For  comparative  analyses  of  separator  skim  milk  by  the  gravi- 
metric method  and  by  the  Babcock  test,  see  Wis.  exp.  station  bull.  52 
and  rep.  XVII,  p.  81;  Conn.  (Storrs)  exp.  station,  bull.  40;  Utah  exp. 
station,  bull.  96.  See  also  Woll,  Testing  skim  milk  by  Babcock  test,  in 
Country  Gentleman,  April  26,  1902.  The  results  obtained  by  the  use  of 
the  Gottlieb  method  have  shown  that!  ether-extraction  methods,  as 


Babcock  Test  for  other  Milk  Products.  89 

98.  The  reason  why  the  Babcock  test  fails  to  show  all 
the  fat  present  in  skim  milk  must  be  sought  in  one  or 
two  causes:  a  trace  of  fat  may  be  dissolved  by  the.sul- 
furic  acid,  or  owing  to  the  minuteness  of  the  fat  glob- 
ules of  such  milk  they  may  not  be  brought  together  in 
the  neck  of  the  bottles  at  the  speed  used  with  the  Bab- 
cock test.  The  latter  cause  is  the  more  likely  explana- 
tion. If  a  drop  of  the  dark  liquid  obtained  in  a  Bab- 
cock bottle  from  a  test  of  whole  milk  be  placed  on  a 
slide  under  the  microscope,  it  will  be  seen  that  a  fair 
number  of  very  minute  fat  globules  are  found  in  the 
liquid.  These  globules  are  not  brought  into  the  column 
of  fat  in  the  neck  of  the  bottle  by  the  centrifugal  force 
exerted  in  the  Babcock  test,  even  if  the  bottles  are 
whirled  in  a  turbine  tester  in  which  they  are  heated 
to  200°  F.  or  higher  (see  71)  ;  the  loss  of  the  fat  con- 
tained in  these  fine  globules  is  compensated  for,  in  the 
testing  of  whole  milk,  by  a  liberal  reading  of  the  fat 
column,  the  reading  being  taken  from  the  bottom  of 
the  fat  to  the  top  of  the  upper  meniscus  (see  p.  35)  ; 
in  some  separator  skim  milk,  on  the  other  hand,  not 
enough  fat  remains  to  completely  fill  the  neck,  and  the 
reading  must  therefore  be  increased  by  from  five-hun- 
dredths  to  one-tenth  of  one  per  cent. 

It  follows  from  what  has  been  said  that  tests  of  skim 
milk  showing  no  fat  in  the  neck  of  the  test  bottles  on 
completion  of  the  test,  generally  indicate  inefficient 
work  of  the  centrifugal  tester  or  of  the  operator,  or  of 

well  as  the  Babcock  test,  give  too  low  results  with  dairy  by-products 
low  in  fat,  like  skim  milk,  butter-milk,  etc.  The  Gottlieb  method  for 
this  reason  has  been  adopted  as  a  standard  for  analysis  of  these  prod- 
ucts by  European  chemists.  (See  254) 


90 


Testing  Milk  and  Its  Products. 


both.  The  test  should  be  repeated  in  such  cases,  using 
more  acid  and  whirling  for  full  five  minutes.  Sepa- 
rator skim  milk  should  be  allowed  to  stand  10  to  15  min- 
utes for  the  air  to  escape  before  the  sample  is  taken. 

In  order  to  bring  as  much  fat  as  possible  into  the 
neck  of  the  bottles  in  testing  skim  milk,  it  is  advisable 
to  add  somewhat  more  acid  than  when 
whole  milk  is  tested,  viz.,  about  20  cc., 
and  to  whirl  the  bottles  at  full  speed  for 
at  least  five  minutes,  keeping  the  tester  as 
hot  as  possible  the  whole  time.1  The  read- 
ings must  be  taken  as  soon  as  the  whirl- 
ing is  completed,  as  owing  to  the  contrac- 
tion of  the  liquid  by  cooling,  the  fat  oth- 
erwise adheres  to  the  inside  of  the  neck 
of  the  test  bottle  as  a  film  of  grease  which 
cannot  be  measured  by  the  scale. 

99.  The  double-necked  test  bottle, 
(fig.  37),  suggested  by  one  of  us,2  is  made 
especially  for  measuring  small  quantities 
of  fat  and  gives  fairly  satisfactory  results 
in  testing  skim  milk  and  butter  milk. 
Each  division  of  the  scale  in  these  bottles 
represents  five-hundredths  of  one  per 


FlG. 


The 


/»  ,,     ,   double-necked 

cent,  and  the  marks  are  so  far  apart  that  skim  miik  bot- 

.,  .     th>     (sometimes 

the  small  fat  column  can  be  easily  esti-  called  the  ohi- 

son   or  B.  &  W. 

mated   to   single   hundredths   of   one   per  bottle.) 

cent.     In  the  first  forms,  now  out  of  use,  the  neck  was 

graduated  to  hundredths  of  one  per  cent. 

1  See  Wis.  exp.  station,  report  XVII,  p.  81. 

2  First  constructed  by  Mr*  J.  J.  Nussbaurner,  of  Illinois;  now  man- 
ufactured by  various  firms. 


Babcock  Test  for  other  Milk  Products.  91 

The  value  of  the  divisions  of  the  scale  on  the  double- 
necked  test  bottles  has  been  a  subject  of  considerable 
discussion,  and  various  opinions  have  been  expressed 
whether  they  show  one-tenth  or  one-twentieth  (.05)  of 
one  per  cent,  of  fat.  By  calibration  with  mercury  the 
value  of  the  divisions  will  be  found  to  be  .05,  or  one- 
twentieth,  of  one  per  cent.,  but  as  shown  above,  the  re- 
sults obtained  in  using  the  bottles  for  separator  skim 
milk  generally  come  at  least  .05  per  cent,  too  low,  so 
that,  practically  speaking,  each  division  may  be  taken 
to  show  one-tenth  of  one  per  cent.,  if  the  fat  fills  only 
one  division  of  the  scale  or  less.1 

The  double-necked  bottle  is  very  convenient  for  the 
testing  of  separator  skim  milk,  thin  butter  milk  and 
whey.  The  milk,  acid  and  water  are  added  to  the  bottle 
through  the  large  side-tube ;  the  mixing  of  milk  and  acid 
must  be  done  with  great  care,  so  that  none  of  the  con- 
tents is  forced  into  the  fine  measuring  tube  and  lost;  it 
is  best  to  add  half  of  the  acid  first  and  mix  it  with  the 
milk,  and  then  add  the  rest.  When  the  fat  is  in  the 
lower  end  of  the  measuring  tube,  it  can  be  forced  into 
the  scale  by  pressing  with  the  finger  on  the  top  of  the 
side  tube. 

In  placing  the  double-necked  bottles  in  the  tester  they 
should  be  put  with  the  filling  tube  toward  the  center  so 
as  to  avoid  any  of  the  fat  being  caught  between  this 
tube  and  the  side  of  the  bottle  when  it  resumes  a  verti- 
cal position. 

This  test  bottle  is  more  fragile  and  expensive  than 
the  ordinary  Babcock  bottles,  and  must  be  carefully 

1  Wis.  exp.  station,  bull.  52;  Penna.  exp.  station,"  report  1896,  p.  221. 


92 


Testing  Milk  and  Its  Products. 


handled ;  it  has  recently  been  made  of  heavier  glass  and 
this  form  is  to  be  highly  recommended.1 

100.  The  double-sized  skim  milk  bottle,  which  was  the 
first  one  recommended  for  the  testing  of  skim  milk,  is  of  no 
particular  value.  It  is  difficult  to  obtain  a  thorough  mixture  of 
the  milk  and  the  acid  in  these  bottles,  and  the  tests  invariably 
come  too  low,  more  so  than  with  the  regular  Babcock  bottles  or 
the  double-necked  skim  milk  bottles,  for  reasons 
that  are  readily  seen. 

101.  Buttermilk    and    whey.      The 
testing  of  buttermilk  or  whey  by  the 
Babcock  test  offers  no  special  difficul- 
ties, and  what  has  been  said  in  regard 
to  tests  of  separator  skim  milk  is  equally 
true  in  case  of  these  by-products.  Whey 
contains  only  a  small  quantity  of  solids 
not  fat,  viz.,  less  than  7  per  cent.   (27), 
and  the  mixing  with  acid  and  the  solu- 
tion of  the  whey  solids  therein  is  there- 
fore readily  accomplished;  the  acid  so- 
lution is  of  a  light  reddish  color,  turn- 
ing black  but  very  slowly. 

TOiz     Riitt^r        "Rntfpr    i<a   not   «sn   pasi'lv^0-88'  Tbe  Wagner 

102.  Duner.     cutter  is    LOI  so  easily  sklm  mllk  Bottle, 
tested  as  other  dairy  products,  both  because  of  the  dif- 
ficulties in  obtaining  a  fair  sample,  and  on  account  of 
the  high  percentage  of  fat  it  contains.    Butter  is  a  me- 
chanical mixture  of  water,  curd,  and  salt,  with  butter- 
fat;  and  the  water  or  brine  is  so  easily  pressed  out  that 
great  care  must  be  taken  to  get  the  same  amount  of 

1  A  double-necked  copper  test  bottle  with  a  detachable  graduated 
glass  neck  was  designed  and  tried  by  one  of  us  a  few  years  ago,  but  It 
was  not  found  to  possess  any  special  advantages  over  the  glass  bottle. 


WAGNERS, 
OUBLE  BOR' 
KiMMED  MILI| 

TESTING  BOTTU 


Babcock  Test  f< 

water  in  the  small  portion  to  be"  LUSltHl  l<\&  exists  in  the 
lot  of  butter  sampled. 

Sampling  butter.  Small  portions  of  butter  are  taken 
with  a  butter  trier  or  a  knife  from  different  parts  of 
the  tub,  package,  or  churning  of  butter  to  be  tested. 
These  small  portions  are  placed  in  a  wide-necked  bottle 
or  jar  which  is  securely  stoppered  and  placed  in  warm 
water  until  the  butter  melts.  The  jar  is  then  shaken 
vigorously  in  order  to  obtain  a  thorough  mixing  of  the 
various  components  of  the  butter,  and  placed  in  cold 
water.  As  the  butter  cools,  the  jar  must  be  shaken  re- 
peatedly until  the  butter  either  solidifies  or  becomes  of 
a  thick  creamy  consistency.  From  this  sample  small 
portions  may  be  taken  for  testing. 

It  is  not  always  necessary  to  prepare  a  sample  of 
butter  for  testing  in  the  manner  described.  If  the  but- 
ter contains  no  loose  drops  of  brine  on  the  freshly-cut 
surface,  a  sample  for  testing  can  be  taken  directly  from 
the  package.  The  operator  must  use  his  judgment  in 
regard  to  the  necessity  of  preparing  a  special  sample  in 
each  case. 

Scales  for  weighing  butter.  In  testing  butter  it  is 
necessary  to  weigh  the  amount  taken  for  a  test  with 
great  accuracy.  Scales  sensitive  to  less  than  .05  should 
be  used,  as  a  difference  of  .1  gram  in  weight  has  a  value 
of  1.0  per  cent,  in  the  result  when  10  grams  of  butter 
are  tested.  Slow-working  scales  with  bearings  that  will 
rust  are  worthless  for  testing  butter.  The  scales  should 
always  be  balanced  before  being  used  and  the  weights 
kept  bright  and  clean. 


94  Testing  Milk  and  Its  Products. 

Carelessness  in  weighing  may  be  the  cause  of  very 
inaccurate  results,  and  the  importance  of  a  sensitive 
scale  cannot  be  over-estimated.  Scales  with  a  graduated 
side  beam  are  preferable  to  those  that  require  the  use 
of  small  weights.  It  is  ,now  possible  to  get  a  scale  that 
is  sensitive  to  .01  gram  on  the  side  beam,  and  permits 
of  20  to  50  grams  of  butter  being  weighed  out  for 
testing.1 

103.  Fat  in  butter.  The  Babcock  test  can  be  used 
with  a  fair  degree  of  accuracy  for  estimating  the  per 
cent,  of  fat  in  butter,  by  weighing  9  grams  of  butter 
into  a  test  bottle  graduated  to  measure  50  per  cent.  fat. 
About  10  cc.  of  hot  water  is  added  to  the  butter,  and 
17.5  cc.  of  sulfuric  acid  of  one-half  the  strength  used  in 
milk  testing.  Mix  the  butter  and  acid  until  the  curd 
is  all  dissolved,  add  hot  water  to  bring  the  fat  into 
the  neck  of  the  test  bottle  and  whirl  in  a  centrifuge. 
When  a  clear  separation  of  the  fat  is  obtained  the  test 
bottle  is  placed  in  water  of  140°  F.  up  to  near  the  top 
of  the  neck  and  after  standing  a  few  minutes  in  this 
water  the  fat  column  is  read  off ;  the  reading  multiplied 
by  2  gives  the  per  cent,  of  fat. 

Accurate  results  can  only  be  obtained  by  taking  great 
care  in  all  the  manipulations,  especially  in  weighing  the 
butter  and  in  reading  the  fat  at  the  proper  tempera- 
ture. Small  errors  in  making  tests  have  a  great  influ- 
ence on  the  results,  because  the  butter  fat  is  such  a 


1  See  bull.  154,  Wisconsin  exp.  sta.,  p.  10. 


Babcock  Test  for  other  Milk  Products.  95 

large  per  cent,  of  the  butter.     Tests  should  always  be 
made  in  duplicate.1 

104.  Cheese.    Cheese  can  be  easily  tested  by  the  Bab- 
cock  test  if  a  small  scale  (fig.  34)  is  at  hand  for  weigh- 
ing the  sample;  the  results  obtained  will  furnish  accu- 
rate information  as  to  the  amount  of  fat  in  the  cheese, 
provided   good    judgment    and    exactness    are    used   in 
sampling    and    weighing    the    cheese.     The    following 
method  of  sampling  cheese  is  recommended  :2 

"  Where  the  cheese  can  be  cut,  a  narrow  wedge  reaching  from 
the  edge  to  the  center  of  the  cheese  will  more  nearly  represent 
the  average  composition  of  the  cheese  than  any  other  sample. 
This  may  be  cut  quite  fine,  with  care  to  avoid  evaporation  of 
water,  and  the  portion  for  analysis  taken  from  the  mixed  mass. 
When  the  sample  is  taken  with  a  cheese  trier,  a  plug  taken  per- 
pendicular to  the  surface,  one-third  of  the  distance  from  the 
edge  to  the  center  of  the  cheese,  will  more  nearly  represent  the 
average  composition  than  any  other.  The  plug  should  either 
reach  entirely  through  or  only  half  way  through  the  cheese. 

"For  inspection  purposes  the  rind  may  be  rejected,  but  for 
investigations,  where  the  -absolute  quantity  of  fat  in  the  cheese 
is  required,  the  rind  should  be  included  in  the  sample.  It  is 
well,  when  admissible,  to  take  two  or  three  plugs  on  different 
sides  of  the  cheese  and  after  splitting  them  lengthwise  with  a 
sharp  knife,  take  portions  of  each  for  the  test." 

105.  When  a  satisfactory  sample  of  the  cheese  has 
been  obtained,  about  5  grams  are  weighed  into  a  milk 
test  bottle,  or  a  larger  quantity  may  be  used  with  a 
cream  test  bottle.   The  test  bottle  is  first  weighed  empty, 
and  again  after  the  pieces  of  cheese  have  been  added. 

1  Special  bottles  for  testing  butter  for  its  fat  content  have  been  put 
on  the  market,  e.  g.,  the  Wagner  Butter  Test  Bottle  and  the  form  sug- 
gested by  H.  R.  Wright,  given  in  the  18th  report  of  the  Iowa  State 
Dairy  Commissioner,  1904,  p.  40. 

2  U.  8.  Dept.  of  Agriculture,  Chemical  Division,  bull.  46,  p.  37. 


96  Testing  Milk  and  Its  Products. 

About  15  cc.  of  warm  water  is  added  to  the  cheese  in 
the  test  bottle,  and  this  is  shaken  occasionally  until  the 
cheese  softens  and  forms  a  creamy  emulsion  with  the 
water.  A  few  cc.  of  acid  will  aid  in  this  mixing  and 
disintegration,  the  process  being  hastened  by  placing 
the  bottles  in  tepid  water.  When  all  lumps  of  cheese 
have  disappeared  in  the  liquid,  the  full  amount  of  acid 
is  added,  and  the  test  completed  in  the  ordinary  man- 
ner. 

The  per  cent,  of  fat  in  the  cheese  is  obtained  by  mul- 
tiplying the  reading  of  the  fat  column  by  18  and  divid- 
ing the  product  by  the  weight  of  cheese.  The  weighing 
of  the  cheese  and  the  reading  of  the  fat  must  be  done 
with  great  care,  since  any  error  introduced  is  more  than 
trebled  in  calculating  the  per  cent,  of  fat  in  the  cheese. 

106.  Condensed  milk.  The  per  cent,  of  fat  in  un- 
sweetened condensed  milk  can  be  obtained  by  weighing 
about  8  grams  into  a  test  bottle  and  proceeding  in  ex- 
actly the  same  way  as  given  under  testing  of  cheese. 
It  is  not  necessary  to  warm  the  condensed  milk  in  the 
test  bottles,  since  the  solution  of  this  in  water  is  readily 
effected.  Enough  water  should  be  added  to  make  the 
total  volume  of  liquid  in  the  bottles  15  to  18  cc. 

If  a  scale  is  not  available  for  weighing  the  sample, 
fairly  accurate  results  may  be  obtained  by  diluting  the 
condensed  milk  with  water  (1:3),  and  completing  the 
test  in  the  ordinary  manner.  When  this  is  done,  the 
results  must  be  corrected"  for  the  dilution  which  the 
sample  received. 

107:  Sweetened  condensed  milk.  The  testing  of 
sweetened  condensed  milk  presents  peculiar  difficulties, 


Babcock  Test  for  other  Milk  Products.  97 

whether  it  is  to  be  tested  by  the  Babcock  test  or  by 
chemical  analysis.  It  may,  however,  be  readily  tested 
by  the  Babcock  test  by  introducing  certain  changes  in 
the  manipulation  of  the  test,  as  worked  out  by  one  of 
us.1  A  brief  description  of  the  manipulations  adopted 
is  here  given. 

About  sixty  grams  of  condensed  milk  are  weighed 
into  a  200  cc.  graduated  flask,  to  this  100  cc.  of  water 
are  added  and  the  solution  of  the  condensed  milk  ef- 
fected. The  flask  is  then  filled  to  the  mark  with  water 
and  after  mixing  thoroughly,  a  17.6  cc.  pipette  full  is 
measured  into  a  Babcock  test  bottle.  About  three  cc. 
of  the  sulfuric  acid  commonly  used  for  testing  milk  are 
then  added  and  the  milk  and  acid  mixed  by  shaking  the 
bottle  vigorously.  The  milk  is  curdled  by  the  acid,  and 
the  curd  and  whey  separated  somewhat.  In  order  to 
make  this  separation  complete  and  to  compact  the  curd 
into  a  firm  lump,  the  test  bottle  is  whirled  for  about  six 
minutes  at  a  rather  high  speed  (1,000  rev.)  in  a  steam- 
heated  turbine  centrifuge. 

The  chamber  in  which  the  bottles  are  whirled  ought 
to  be  heated  to  about  200°  F.  This  can  be  done  either 
by  the  turbine  exhaust  steam  which  leaks  into  the  test- 
bottle  chamber  of  some  machines,  or  by  means  of  a 
valve  and  pipe  which  will  allow  steam  to  be  turned  di- 
rectly into  the  test  bottle  chamber.  After  this  first 
whirling  the  test  bottles  are  taken  from  the  centrifuge 
and  by  being  careful  not  to  break  the  lump  of  curd 
nearly  all  the  whey  or  sugar  solution  can  be  poured  out 
of  the  neck.  Ten  cc.  of  water  are  then  poured  into  the 

1  Wis.  exp.  station,  report  XVII,  pp. 
7 


98  Testing  Milk  and  Its  Products. 

test  bottle  and  the  curd  is  shaken  up  with  it  so  as  to 
wash  out  more  of  the  sugar.  Three  cc.  of  acid  are  now 
added  as  before  and  the  test  bottle  whirled  a  second 
time  in  the  centrifuge.  The  whey  is  decanted  again 
and  this  second  washing  removes  so  much  of  the  sugar 
that  what  remains  will  not  interfere  with  testing  in  the 
usual  way.  The  curd  remaining  in  the  bottle  after  the 
second  washing  is  shaken  up  with  ten  cc.  of  water;  the 
water-emulsion  of  the  curd  is  then  cooled ;  the  usual 
amount,  17.5  cc.,  of  sulfuric  acid  is  added,  and  the  test 
completed  in  the  same  way  as  when  milk  is  tested.  The 
amount  of  fat  obtained  in  the  neck  of  the  test  bottle  is 
calculated  to  the  weight  of  condensed  milk  taken.1 

108.  Ice  cream.  Methods  for  determining  the  per 
cent,  of  fat  in  ice  cream  have  recently  been  worked  out 
by  Holm2  and  Howard.3  The  former  recommends  the 
use  of  a  mixture  of  equal  parts  of  hydrochloric  and 
glacial  acetic  acid,  in  the  place  of  sulfuric  acid,  as  the 
latter  is  likely  to  char  the  sugar  in  the  ice  cream,  thus 
giving  difficulty  in  reading  the  results.  Nine  grams  of 
the  sample  are  weighed  into  a  Babccck  milk  bottle, 
which  is  then  filled  almost  to  the  neck  with  the  mixture 
of  the  two  acids  given.  This  is  then  heated  for  a  few 
minutes  until  black,  when  the  bottle  is  whirled  in  the 
tester  and  water  added  to  bring  the  fat  column  within 
the  graduations  of  the  neck,  as  in  the  regular  Babcock 
test.  The  reading  multiplied  by  two  gives  the  per  cent, 
of  fat  in  the  ice  cream. 

1  The  Gottlieb  method  gives  very  satisfactory  results  with  both 
cheese  and  condensed  milk  (see  2f>i). 

2  Report  Dept.  of  Health,  City  of  Chicago,  1006,  p.  50. 

3  Journ.  Am.  Ohem.  Soc.,  1907,  p.  16. 


Babcock  Test  for  other  Milk  Products.  99 

Questions. 

1.  Why  is  it  difficult  to  get  accurate  tests  of  skim  milk  by 
the  Babcock  test? 

2.  Mention   at   least    three   precautions   that   should   be    taken 
in    testing   skim    milk. 

3.  Should   more    acid   be   used    for   full   milk    than    for    skim 
milk,   or   more  for  skim  milk  than  for  whey?     Why? 

4.  How  much   fat   is   probably   present   in   a  sample   of   skim 
milk  which  shows  no  fat  on  being  tested  in  a  skim  milk  bottle? 

5.  What    per    cent,    of    fat   does    each    division    of    a    double- 
necked  skimmilk   test  bottle  represent? 

6.  How   can    (a)    butter,    (b)    cheese,    (c)    condensed  milk  be 
tested  with  the  Babcock  test? 

7.  If  8.4  gr.  cheese  give  a  reading  of  12.2%  on  the  neck  of  a 
test  bottle,  what  per  cent,  of  fat  does  the  cheese  contain? 

8.  What  is  the   per   cent,   of   fat  in   a  sample  of   cheese,  of 
which   4.2   grams   contained   enough   fat  to   fill  the   space   in   the 
neck  of  a  Babcock  milk  test  bottle  from  1.7  to  9.5  mark! 

9.  How  can  the  per  cent,  of  fat  in  ice  cream  be  determined? 


CHAPTER  VI. 

• 

THE    LACTOMETER    AND     ITS    APPLICATION. 

109.  The  lactometer  is  used  for  determining  the  spe- 
cific gravity  of  milk.  The  term  specific  gravity  means 
the  weight  of  a  certain  volume  of  a  solid  or  a  liquid 
substance  compared  with  the  weight  of  the  same  vol- 
ume of  water  at  4°  C.  (39.2°  Fahr.)  ;  for  gases  the 
standard  of  comparison  is  air  or  hydrogen.  If  the  milk 
which  a  can  will  hold  weighs  exactly  103.2  Ibs.,  this  can 
will  hold  a  smaller  weight  of  water,  say  100  Ibs.,  as  milk 
is  heavier  than  water;  the  specific  gravity  of  this  milk 
will  then  be  1^=1.032. 

The  specific  gravity  of  normal  cow's  milk  will  vary 
in  different  samples  between  1.029  and  1.035  at  60°  F., 
the  average  being  about  1.032.  The  specific  gravity  of 
skim  milk  is  about  1.036-1.038,  and  of  sweet  cream  1.01 
to  .95,  according  to  the  per  cent,  of  fat  contained  there- 
in; average  specific  gravity  1.0  (see  p.  76). 1 

The  lactometer  enables  us  to  determine  rapidly  the 
relative  weight  of  milk  and  water.  Its  application  rests 
on  well-known  laws  of  physics :  When  a  body  floats  in 
a  liquid,  the  weight  of  the  amount  of  liquid  which  it 
replaces  is  equal  to  the  weight  of  the  body.  It  will  sink 
further  into  a  light  liquid  than  into  a  heavy  one.  be- 

1  Since  1  gallon  of  water  weighs  8.34  Ibs.,  1  prnl.  milk  will  wi-iirh  *.:',! 
XI. 032  or  8.6  Ibs. ;  1  gal.  of  skim  milk,  8.7  Ibs.,  and  1  gal.  of  cream  from  s 
to  8.4  Ibs.,  according  to  its  richness. 


The  Lactometer  and  Its  Application. 


101 


cause  a  larger  volume  of  the  former  will 
be  required  to  equal  the  weight  of  the 
body.  A  lactometer  will  therefore  sink 
deeper  into  milk  of  a  low  specific  grav- 
ity than  into  milk  of  a  high  specific 
gravity. 

no.  The  Quevenne  lactometer. 
This  instrument  (fig.  39),  consists  of 
a  hollow  cylinder  weighted  by  means  of 
mercury  or  fine  shot  so  that  it  will  float 
in  milk  in  an  upright  position,  and  pro- 
vided with  a  narrow  stem  at  its  upper 
end,  inside  of  which  is  found  a  gradu- 
ated paper  scale.  In  the  better  forms, 
like  the  Quevenne  lactometer  shown  in 
the  figure,  a  thermometer  is  melted  into 
the  cylinder,  with  its  bulb  at  the  lower 
end  of  the  lactometer  and  its  stem  ris- 
ing above  the  lactometer  scale. 

The  scale  of  tne  Quevenne  lactometer 
is  marked  at  15  and  40,  and  divided  into 
25  equal  parts,  with  figures  at  each  five 
divisions  of  the  scale.  The  single  divis- 
ions are  called  degrees.  The  15-degree 
mark  is  placed  at  the  point  to  which  the 
lactometer  will  sink  when  lowered  into 
a  liquid  of  a  specific  gravity  of  1.015, 
and  the  40-degree  mark  at  the  point  to 
which  it  will  sink  when  placed  in  a 
liquid  of  a  specific  gravity  of  1.040. 


d£ai5)?tln  °ylin" 


102  Testing.  Milk  and  Its  Products. 

The  specific  gravity  is  changed  to  lactometer  degrees 
by  multiplying  by  1000  and  subtracting  1000  from  the 
product. 

EXAMPLE:  Given,  the  specific  gravity  of  a  sample  of  milk, 
1.0345;  corresponding  lactometer  degree,  1.0345X1000 — 1000= 
34.5. 

Conversely,  if  the  lactometer  degree  is  known,  the 
corresponding  specific  gravity  is  found  by  dividing  by 
1000  and  adding  1  to  the  quotient  (34.5-r-1000=0345; 
.0345+1=1.0345). 

in.  Influence  of  temperature.  Like  most  liquids, 
milk  will  expand  on  being  warmed,  and  the  same  vol- 
ume will,  therefore,  weigh  less  when  warm  than  before ; 
that  is,  its  specific  gravity  will  be  decreased.  It  follows 
then  that  a  lactometer  is  only  correct  for  the  tempera- 
ture at  which  it  is  standardized.  If  a  lactometer  sinks 
to  the  32-mark  in  a  sample  of  milk  of  a  temperature  of 
60°  F.,  it  will  only  sink  to,  say  33,  if  the  temperature 
of  the  milk  is  50°  F.,  and  will  sink  farther  down,  e.  g., 
to  31,  if  the  temperature  is  70°  F.  Lactometers  on  the 
market  at  present  are  generally  standardized  at  60°  F., 
and  to  show  the  correct  specific  gravity  the  milk  to  be 
tested  should  first  be  warmed  (or  cooled,  as  the  case 
may  be)  to  exactly  60°  F.  As  this  is  a  somewhat  slow 
process,  tables  have  been  constructed  for  correcting  the 
results  for  errors  due  to  differences  in  temperature  (see 
Appendix,  Table  V). 

112.  As  the  fat  content  of  a  sample  of  milk  has  a 
marked  influence  on  its  specific  gravity  at  different 
temperatures,  the  co-efficient  of  expansion  of  fat  differ- 
ing greatly  from  that  of  the  milk  serum,  the  table  can- 


The  Lactometer  and  Its  Application.  103 

not  give  absolutely  accurate  corrections  for  all  kinds  of 
milk,  whether  rich  or  poor.  But  the  error  introduced 
by  the  use  of  one  table  for  any  kind  of  whole  milk 
within  a  comparatively  small  range  of  temperature,  like 
ten  degrees  above  or  belcw  60°,  is  too  small  to  have  any 
importance  outside  of  exact  scientific  work,  and  in  such, 
the  specific  gravity  is  always  determined  by  means  of  a 
picnometer  or  a  specific-gravity  bottle  (248),  at  the  exact 
temperature  at  which  this  has  been  calibrated.  In  tak- 
ing the  specific  gravity  of  a  sample  of  milk  by  means 
of  a  lactometer,  the  milk  is  always  warmed  or  cooled 
so  that  its  temperature  does  not  vary  ten  degrees  either 
way  from  60°  F. 

113.  The  temperature  correction  table  for  whole  milk, 
given  in  the  Appendix  shows  that  if,  e.  g.,  the  specific 
gravity  of  a  sample  of  milk  taken  at  68°  F.  was  found 
to  be  1.034,  its  specific  gravity  would  be  1.0352  if  the 
milk  was  cooled  down  to  60°.  If  the  specific  gravity 
given  was  found  at  a  temperature  of  51°,  the  corrected 
specific  gravity  of  the  milk  would  be  1.0329. 

In  practical  work  in  factories  or  at  the  farm,  suffi- 
ciently accurate  temperature  correcticns  may  generally 
be  made  by  adding  .1  to  the  lactometer  reading  for 
each  degree  above  60°  F.,  and  subtracting  .1  for  each 
degree  below  60°  ;  e.  g.,  if  the  reading  at  64°  is  29.5. 
it  will  be  about  29.5+.4=29.9  at  60°  F. ;  and  34.0  at 
52°  F.  will  be  about  34.0— .8=33.2  at  60°  F.  The  table 
in  the  Appendix  gives  33.0  as  the  corrected  figure  in 
both  cases. 

The  scale  of  the  thermometer  in  the  .lactometer  should 
be  placed  above  the  lactometer  scale  so  that  the  tern- 


104  Testing  Milk  and  Its  Products. 

perature  may  be  read  without  taking  the  lactometer  out 
of  the  milk;  this  will  give  more  correct  results,  will 
facilitate  the  reading  and  save  time. 

114.  N.  Y.  Board  of  Health  lactometer.  In  the  East,  and 
among  city  milk  inspectors  generally,  the  so-called  New  York 
Board  of  Health  lactometer  is  often  used.  This  does  not  give 
the  specific  gravity  of  the  milk  directly,  as  is  the  case  with  the 
Quevenne  lactometer;  but  the  scale  is  divided  into  120  equal 
parts,  known  as  Board  of  Health  degrees,  the  mark  100  being 
placed  at  the  point  to  which  the  lactometer  sinks  when  lowered 
into  milk  of  a  specific  gravity  of  1.029  (at  60°  F.) ;  this  is  con- 
sidered the  lowest  limit  for  the  specific  gravity  of  normal  cow's 
milk.  The  zero  mark  on  the  scale  shows  the  point  to  which  the 
lactometer  will  sink  in  water;  the  distance  between  these  two 
marks  is  divided  into  100  equal  parts,  and  the  scale  is  contin- 
ued below  the  100  mark  to  120.  As  100°  on  the  Board  of  Health 
lactometer  corresponds  to  29°  on  the  Quevenne  lactometer,  the 
zero  mark  showing  in  either  case  a  specific  gravity  of  1,  the 
degrees  on  the  former  lactometer  may  easily  be  changed  into 
Quevenne  lactometer  degrees  by  multiplying  by  .29.  To  fur- 
ther aid  in  this  transposition,  Table  III  is  given  in  the  Appen- 
dix, showing  the  readings  of  the  two  scales  between  60°  and 
120°  on  the  Board  of  Health  lactometer. 

115.  Reading  the  lactometer.  For  determining  the 
specific  gravity  of  milk  in  factories  or  private  dairies, 
tin  cylinders,  l1/^  inches  in  diameter  and  10  inches 
high,  with  a  base  about  four  inches  in  diameter,  are 
recommended  (see  fig.  39)  ;  another  form  of  specific- 
gravity  cylinder,  in  use  in  chemical  laboratories,  is 
shown  in  fig.  40.  The  cylinder  is  filled  with  milk  of  a 
temperature  ranging  between  50°  and  70°  F.,  to  within 
an  inch  of  the  top,  and  the  lactometer  is  slowly  lowered 
therein  until  it  floats;  it  is  left  in  the  milk  for  about 
half  a  minute  before  lactometer  and  thermometer  read- 


The  Lactometer  and  Its  Application.  105 

• 
ings  are  taken,  both  to  allow  the  escape  of  air  which 

has  been  mixed  with  the  milk  in  pouring  it,  prepara- 
tory to  the  specific-gravity  determination,  and  to  allow 
the  thermometer  to  adjust  itself  to  the  tem- 
perature of  the  milk.  The  lactometer  should 
not  be  left  in  the  milk  more  than  a  minute 
before  reading  is  taken,  as  cream  will  soon 
begin  to  rise  on  the  milk,  and  the  reading, 
if  taken  later,  will  be  too  high,  as  the  bulb 
of  the  lactometer  will  be  floating  in  partially 
skimmed  milk  (23).  In  reading  the  lacto- 
meter degree,  the  mark  on  the  scale  plainly 
visible  through  the  upper  portion  of  the 
meniscus  of  the  milk  should  be  noted.  Ow- 
ing to  surface  tension  the  milk  in  immediate 
contact,  with  the  lactometer  stem  will  rise 
above  the  level  of  the  surface  in  the  cylinder,  cylinder- 
and  this  must  be  taken  into  consideration  in  reading 
the  degrees.  It  is  not  necessary  to  read  closer  than  one- 
half  of  a  lactometer  degree  in  the  practical  work  of  a 
factory  or  a  dairy. 

116.  Time  of  taking  lactometer  readings.  The  spe- 
cific gravity  of  milk  should  not  be  determined  until  an 
hour  or  two  after  the  milk  has  been  drawn  from  the 
udder,  as  too  low  results  are  otherwise  obtained  (Reck- 
nagel's  phenomenon).1  The  cause  of  this  phenomenon 
is  not  definitely  understood;  it  may  come  from  the  es- 
cape of  gases  in  the  milk,  or  from  changes  occurring  in 
the  mechanical  condition  of  the  nitrogenous  compo- 

1  Milchztg.  1883,  419;  bull.  43,Ohem.  Div.,  U.S.  Dept.  of  Agriculture, 
p.  191;  Analyst,  1894,  p.  76. 


106  Testing  Milk  and  Its  Products. 

nents  of  the  milk.  The  results  obtained  after  a  couple 
of  hours  will,  as  a  rule,  come  about  one  degree  higher 
than  when  the  milk  is  cooled  down  directly  after  milk- 
ing and  its  specific  gravity  then  determined. 

117.  Influence   of   solid   preservatives  on   lactome- 

•* 
ter  readings.     When  potassium  bi-chromate,  corrosive 

sublimate,  etc.,  is  added  to  milk  samples  to  preserve 
them  from  souring  (190),  the  specific  gravity  of  the 
milk  will  be  increased ;  with  the  quantity  usually  added 
(%  g^am  to  a  pint  of  milk)  the  increase  amounts  to 
about  1  lactometer  degree,  and  this  correction  of  lacto- 
meter readings  should  be  made  with  milk  samples  pre- 
served in  this  manner.  To  avoid  this  error,  Dr.  Eich- 
loff1  recommends  the  use  of  a  solution  of  potassium  bi- 
chromate in  water  (43  grams  to  1  liter),  the  specific 
gravity  of  which  is  1.032,  or  similar  to  that  of  average 
milk;  5  cc.  of  this  solution  is  required  for  a  pint  of 
milk.  No  correction  is  necessary  for  the  dilution  with 
this  small  amount  of  liquid  preservative. 

118.  Cleaning  of  lactometer.    The  lactometer  should 
be  cleaned  directly  after  using,  by  rinsing  with  cold 
water;   it  is  then  wiped  dry   with  a  clean  cloth  and 
placed  in  the  case.  * 

n8a.  Testing  the  accuracy  of  lactometers.  The 
correctness  of  lactometers  may  be  determined  with  a 
fair  degree  of  accuracy  by  placing  them  in  different 
salt  solutions  prepared  by  dissolving  exactly  3,  4,  and  5 
grams  of  pure  dairy  salt  in  100  grams  (cc.)  of  water. 
The  specific  gravities  at  60°  F.  of  solutions  thus  (>b- 

1   'IVrlmik  <!«•!•  MNrhpriifiintr.  p.  98. 


The  Lactometer  and  Its  Application.  107 

tained  are  1.022,  1.029,  and  1.036,  for  3,  4,  and  5  per 
cent,  solutions,  respectively. 

CALCULATION  OF  MILK  SOLIDS. 

1 19**  A  number  of  chemists  have  prepared  formulas 
for  the  calculation  of  milk  solids  when  the  fat  content, 
and  the  specific  gravity  (lactometer  reading)  of  the 
milk  are  known.  By  careful  work  with  milk  tester  and 
lactometer  it  is  possible  by  means  of  these  formulas  to 
determine  the  compcsition  of  samples  of  milk  with  con- 
siderable accuracy  both  outside  of  and  in  chemical  lab- 
oratories. As  the  .complete  formulas  given  by  various 
chemists  (Behrend  and  Morgen,  Clausnitzer  and  Mayer, 
Fleischmann,  Hehner  and  Eichmond,  Eichmond,  Bab- 
cock)1  are  very  involved,  and  require  rather  lengthy 
calculations,  tables  facilitating  the  figuring  have  been 
prepared.  The  formulas  in  use  at  the  present  time,  in 
this  country  and  abroad,  are  those  proposed  by  Fleisch- 
mann,  Hehner  and  Eichmond,  or  Babcock.  Babcock's 
formula  is  the  one  generally  taught  in  American  dairy 
schools  and  is  therefore  given  here;  it  forms  the  foun- 
dation for  Table  VI  in  the  Appendix  for  calculation  of 
solids  not  fat. 

By  the  use  of  these  tables  the  percents  of  solids  not 
fat  may  be  found,  corresponding  to  lactometer  read- 
ings from  26  to  36,  and  to  fat  contents  from  0  to  6 
per  cent.  The  formula,  as  amended  in  1895,2  is  as  fol- 
lows, 8  being  the  specific  gravity  and  /  the  per  cent,  of 
fat  in  the  milk. 

1  Agricultural  Science,  vol.  Ill,  p.  139. 

2  Wisconsin  experiment  station,  twelfth  report,  page  120. 


108  Testing  Milk  and  Its  Products. 

SolSdB  not  fat=(IJ^fgf-l)(100-f)  2.5 

The  derivation  of  this  formula  is  explained  in  the  re- 
port referred  to. 

120.  Short  formulas.  The  tables  made  up  from  this 
formula,  giving  the  percentages  of  solids  not  fat  corre- 
sponding to  certain  per  cents,  of  fat  and  lactometer 
readings,  are  given  in  the  Appendix.  A  careful  exam- 
ination of  the  tables  will  disclose  the  fact  that  the  per 
cent,  of  solids  not  fat  increases  uniformly  at  the  rate 
of  .25,  or  one-fourth  of  a  per  cent,  for  each  lactometer 
degree,  and  .02  per  cent,  for  each  tenth  of  a  per  cent,  of 
fat.  This  relation  is  expressed  by  the  following  simple 
formulas : 

Solids  not  f  at=%  L  -f  .2  f 
Total  solids=%  L  +  1.2  f, 

L  being  the  lactometer  reading  at  60°  F.  (specific  gravity 
X  1000  —  1000),  and  f  the  per  cent,  or  fat  in  the  milk. 

Eule:  a,  To  -find  the  per  cent,  of  solids  not  fat  in  milk,  add 
two-tenths  of  the  per  cent,  of  fat  to  one- fourth  of  the  lacto- 
meter reading,  and 

b,  To  find  the  per  cent,  of  total  solids  in  millc,  add  one  and 
two-tenths  times  the  per  cent,  of  fat  to  one-fourth  of  the  lacto- 
meter reading. 

These  formulas  and  rules  are  easily  remembered  and 
can  be  quickly  applied  without  the  use  of  tables.  The 
results  obtained  by  using  them  do  not  differ  more  than 
.04  per  cent,  from  those  of  the  complete  formula  for 
milks  containing  up  to  6  per  cent,  of  fat,  and  may  be 
safely  relied  upon  in  practical  work. 

The  English  dairy  chemist  Droop  Richmond  has 
constructed  an  ingenious  sliding  "milk  scale'7  which  en- 
ables one  to  readily  find  the  percentages  of  total  solids 


The  Lactometer  and  Its  Application.  109 

corresponding  to  different  lactometer  readings  and  fat 
contents,  or  the  percentage  cf  fat  from  total  solids  and 
lactometer  readings.1 

ADULTERATION  OF  MILK. 

121.  Methods  of  adulteration.  The  problem  of  de- 
termining whether  or  not  a  sample  of  milk  is  adulter- 
ated becomes  an  important  one  in  the  work  of  milk  in- 
spectors and  dairy  and  food  chemists.  Managers  of 
creameries  and  cheese  factories  are  also  sometimes  in- 
terested in  ascertaining  possible  adulterations  in  the 
case  of  some  patron's  milk,  although  at  present,  since 
the  general  introduction  of  the  Babcock  test  in  factories 
and  the  payment  for  the  milk  on  the  basis  of  the  amount 
of  butter  fat  delivered,  the  temptation  to  water  or  skim 
the  milk  has  been  largely  removed.  In  the  city  milk 
trade,  especially  in  our  larger  cities,  watered  or  skimmed 
milk  is  still  frequently  met  with,  in  spite  of  the  vigi- 
lance of  their  milk  inspectors  or  the  officers  of  the  city 
boards  of  health. 

When  the  origin  of  a  suspected  sample  of  milk  is 
known,  a  second  sample  should  always  be  taken  on  the 
premises,  if  possible,  by  or  in  the  presence  of  the  in- 
spector, and  the  composition  of  the  two  samples  com- 
pared. If  the  suspected  sample  is  considerably  lower 
in  fat  content  than  the  second,  so-called  control-sample, 
and  has  a  normal  per  cent,  of  solids  not  fat,  it  is 
skimmed;  if  the  solids  not  fat  are  below  normal,  it  is 
watered;  and  if  both  these  percentages  are  abnormally 
low,  the  sample  is  most  likely  both  watered  and 
skimmed  (126). 

1  Dairy;Ohemistry,*page  61. 


110  Testing  Milk  and  Its  Products. 

122.  Latitude  of  variation.     In  order  to  determine 
whether  or  not  a  sample  of  milk  is  skimmed  or  watered, 
or  both  skimmed  and  watered,  the  per  cents,  of  fat  and 
of  solids  not  fat  in  the  sample  must  be  ascertained,  and 
if  a   control-sample   can   be  secured,   these   determina- 
tions for  both  samples  compared.     The  proper  latitude 
to  be  allowed  for  the  natural  variation  in  the  com 
tion  of  milk  differs  according  to  the  origin  of  the  milk ; 
in  case  of  milk  from  single  cows,  the  variations  in  fat 
content  from  day  to  day  may  exceed  one  per  cent.,  al- 
though under  ordinary  conditions  the  per  cent,  of  fat 
in  most  cow's  milk  will  not  vary  that  much.     The  con- 
tent of  solids  not  fat  is  more  constant,  and  rarely  va- 
ries one-half  of  one  per  cent,   from  day  to  day  with 
single  cows.  Cows  in  heat  or  sick  cows  may  give  milk  dif- 
fering considerably  in  composition  from  normal  milk^X 

123.  Mixed  herd  milk  is  of  comparatively  uniform     * 
composition  on  consecutive  days,  and  as  most  milk  of- 
fered for  sale  or  delivered  to  factories  is  of  this  kind, 
the  task   of  the  milk   inspector  is  made  considerably 
easier  and  more  certain  on  this  account.     Daily  varia- 
tions in  herd  milk  beyond  one  per  cent,  of  fat  and  one- 
half  per  cent,  of  solids  not  fat,  are  suspicious  and  may 

be  taken  as  fairly  conclusive  evidence  of  adulteration. 
This  is  especially  true  in  case  the  control  -sample  sho  ws  n 
comparatively  low  content  of  fat  or  solids  not  fat  (159). 

124.  Legal  standards.     Where  a  control-sample  can- 
not be  taken,  the  legal  standards  of  the  various  states 
for  fat  or  solids  in  milk  are  used  as  a  basis  for  calculat- 

1  Blythe,  Foods,  their  Composition  and  Analysis,  London,  1903,  p. 
250  et  seq. 


The  Lactometer  and  Its  Application.  Ill 

ing  the  extent  of  adulteration  of  a  sample  of  milk.  A 
list  of  legal  standards  for  milk  in  this  country  and 
abroad  is  given  in  the  Appendix.  These  standards  de- 
termine the  limits  below  which  the  milk  offered  for  sale 
within  the  respective  states  must  not  fall.  Legally  it 
matters  not  whether  a  sample  of  milk  offered  for  sale 
has  beo^l  skimmed  or  watered  by  the  dealer  or  by  the- 
cow ;  i^  the  latter  case,  the  cows  producing  the  milk  are 
of  a  breed  or  a  strain  that  has  been  bred  persistently 
for  quantity  of  milk,  without  regard  to  its  quality.  In 
most  states  the  legal  standard  for  the  fat  content  of 
milk  is  3  per  cent.,  and  for  solids  not  fat  9  per  cent. 
There  are,  however,  cows  which  at  times  produce  milk 
containing  only  2.5  to  2.8  per  cent,  of  fat,  and  less  than 
8.5  per  cent,  solids  not  fat.  Such  milk  cannot  therefore 
j  be  legally  sold  in  most  states  in  the  Union,  and  the  far- 
f  mer  offering  such  milk  for  sale,  even  if  he  does  not 
know  the  composition  of  the  milk  produced  by  his  cows 
is  as  liable  to  prosecution  as  if  he  had  directly  watered 
the  milk.  By  mixing  the  milk  of  several  cows,  the 
chances  are  that  the  mixed  milk  will  contain  more  fat 
and  solids  not  fat  than  called  for  by  the  legal  standard ; 
if  such  should  not  be  the  case,  cows  producing  richer 
milk  must  be  added  to  the  herd  so  as  to  raise  the  qual- 
ity of  the  herd  milk  up  to  the  legal  standard,  or  the 
cows  giving  very  thin  milk  must  be  disposed  of. 

125.  The  specific  gravity  of  the  milk  solids.  A  calcula- 
tion of  the  specific  gravity  of  the  milk  solids  is  of  considerable 
assistance  in  interpreting  the  results  of  analyses  of '  suspected 
milk  samples.  The  milk  solids  vary  but  slightly  in  specific 
gravity,  viz.,  between  1.25  and  1.34,  the  richer  milks  having  sol- 
ids of  low  specific  gravities.  The  specific  gravity  of  the  milk 
solids  is  calculated  by  means  of  Fleischmann  's  formula 


112  Testing  Milk  and  Its  Products. 


~t      100  s-100 

s 

S  being  the  sp.  gr.  of  the  milk  solids,  s  that  of  the  milk  and  t 
the   total  solids   of   the  milk. 

Example:  A  sample  of  milk  has  been  found  to  contain  13.0 
per  cent,  of  solids,  sp.  gr.  1.032;  then a  °  °^-||~1-^=3.101; 
13.0—3.101=9.899;  -1-^°-  =1.31r=the  specific  fltvity  ol  the  milk 

9-899  ^ 

solids. 

The  specific  gravity  of  the  solids  does  not  change  if  ^he  milk 
is  watered,  while  it  is  increased  when  the  milk  is  skimmed.  If  *a 
sample  of  milk  of  the  composition  given  in  the  preceding  e^.- 
ample  had  been  watered  so  as  to  reduce  the  solids  to  11.7  per 
cent,  and  .the  specific  gravity  to  1.0291  (as  would  be  the  case 
when  10  per  cent,  of  water  was  added),  we  would  again  have, 
by  calculation  as  above,  S=1.31.  If,  on  the  other  hand,  the 
milk  was  skimmed  so  as  to  reduce  the  solids  to  11.7  per  cent., 
thereby  increasing  the  specific  gravity  of  the  milk  to,  say  1.035, 
we  would  have  by  substituting  these  values  in  the  preceding 
formula,  S=1.41,  showing  conclusively  that  the  milk  had  been 
skimmed. 

An  addition  of  skim  milk  to  whole  milk  would  have  the  same 
effect  as  skimming,  as  regards  the  composition  of  the  latter,  and 
the  specific  gravity  of  its  solids. 

The  specific  gravity  of  pure  butter  fat  at  60°  F.  is  .93,  and 
of  the  fat-free  milk  solids,  1.5847  (Fleischmann).  The  solids  of 
skim  milk  have  a  specific  gravity  of  1.56.  Samples  of  whole 
milk,  the  solids  of  which  have  a  specific  gravity  above  1.34  are 
suspicious,  and  a  specific  gravity  over  1.40  is  conclusive  evidence 
of  skimming. 

To  facilitate  the  calculation  of  the  specific  gravity  of  milk 
solids,  Table  IV  is  given  in  the  Appendix,  showing  at  a  glance 
the  value  of  1  °  °  8~ 1  °  °  for  specific  gravities  between  1.019  and 
1.0369.  An  example  will  readily  illustrate  the  use  of  the  table. 

Example:  A*  sample  of  milk  has  a  specific  gravity  of  1.0343 
and  contains  12.25  per  cent,  solids.  In  Table  IV,  we  find  in  the 
horizontal  line  beginning  with  1.034  under  the  column  headed 
0.0003,  the  figure  3.316,  which  is  the  value  for  10°8~100  when 


The  Lactometer  and  Its  Application.  113 

s=1.0343.  Introducing  this  value  and  that  of  the  total  solids 
in  the  formula,  the  calculation  is  12.25—3.316=8.934;  12.25-^ 
8.934=1.37,  which  is  the  specific  gravity  of  the  solids  in  this 
case. 

126.  To  recapitulate.  Adulteration  of  milk  by  water- 
ing or  skimming  or  bcth  may  be  established  by  a  com- 
parison of  the  composition  of  the  suspected  sample  with 
that  of  a  control-sample,   or  if  none  such  can  be  ob- 
tained, with  the  legal  standards.     If  the  composition  of 
the  two  samples  varies  appreciably,  the  milk  has  been 
adulterated,   and  the  character  of  the  adulteration  is 
shown  from  the  following  statement : 

If  the  analysis  of  the  suspected  sample 
shows 

sp.  gr.  of  milk )  ,  ] 

fat  and  solids  not  fat ,. /  >       watered 

gr.  of  solids \ ., . ._._._ normal  ) 

sp.  gr.  of  milk  and  of  solids )  »  .  *        *  1 

solids  not  f at \  m££|  L     skimmed 

J:at  and  solids JcJK —  J 

~"sp\gr.  °f  milk "*. normal  v  J        watered 

sp.'gr.  of  solids normal  or  high  >  and 

fat  and  solids  not  fat low  )      skimmed 

The  extent»of  the  adulteration  is  determined  as  given 
below.  k  • 

127.  ^fcWation  of  extent  of  adulteration.1     In  the 

following  fyPffil*w  percentages  found  in  the  control- 
samples,  if  sucrHfrfc  at  hand,  are  always  substituted  for 
the  legal  standarcfe, 

a.  Skimming. — 1.  If  a  sample  of  milk  has  been 
skimmed,  the  following  formula  will  give^he  number 
cf  pounds  cf  f  at  *abstr  acted  from  lOO^il^V^f  milk: 

Fat  abstracted=legal  standard  for  fat — f,  .  .  (I) 
f  being  the  per  cent,  of  fat  in  the  suspected  sample. 

1  Well,  Handbook  for  Farmers  and  Dairymen,  New  York,  1907,  pp. 

267-8. 

8 


114  Testing  Milk  and  Its  Products. 

2.  The  following  formula  will  give  the  per  cent,  of 
fat  abstracted,  calculated  on  the  total  quantity  of  fat 
originally  found  in  the  milk: 

x=100 fxioo n 

legal  standard  for  fat 

b.  Watering.— If  a   sample  is  watered,   the   calcula- 
tions are  mcst  conveniently  based  on  the  percentage  of 
solids  not  fat  in  the  milk.     The  percentage  adulteration 
may  be  expressed   either   on  basis   of   the   amount  of 
water  present  in  the  adulterated  milk,  or  the  amount  of 
water  added  to  the  original  milk: 

1.  Percent,  of  foreign  (extraneous)  water  in  the  adul- 

,     ,  ,     .„     ln, sxioo 

terated  milk=10Q—^ — r—  — ^ — T~S ?T3 —    ,  n  .  (Ill) 

legal  standard  tor  solids  not  tat 

S  being  the  per  cent,  of  solids  not  fat  in  the  suspected 
sample. 

Example:  A  sfiple  of  milk  contains  7.5  per  cent,  solids  not 
fat;  if  the  legal  standard  for  solids  not  fat  is  9  per  cent.,  then 
100 —  7.5*1  ^-=16.7,'  shows  the  per  cent,  of  extraneous  water 
in  the  milk. 

2.  Watering  of  milk  may  also  be  expressed  in  per 
cent,  of  water  added  to  the  original  milk,  by  "formula  IV : 

Per  cent,  of  water  added  to  the  o 

100 X  leg.   stand,    for  sol.   dfi 
=-  -g-  -^--100     (IV) 

%*" 
In  the  example  given  above,  l™^?— 100=20  percent. 

of  water  was  added  to  the  original  milk. 

c.  Watering  and  skimming. — If  a  Cample  has   been 
both  watered  f*nd  skimmed,  the  extent  of  watering  is 
ascertained  by  means  of  formula    (III)    or   (IV),   and 
the   fat   abstracted   found   according   to   the   following 
formula : 


The  Lactometer  and  Its  Application.  115 

Per  cent,  fat  abstracted= 

leg.  stand,  for  sol.  not  fat 
leg.  stand,  for  fat — ^ —  —  Xf.      .      .     (V) 

Example:  A  sample  of  milk  contains  2.4  per  cent,  of  fat  and 
8.1  per  cent,  solids  not  fat;  then 

Extraneous   water   in   milk=100-  8- lx^  °  °:=10   per    cent. 

Fat  abstracted=3— ^|^=33  per  cent. 

100  Ibs.  of  the  milk  contained  10  Ibs.  of  extraneous  water  and 
.33  Ib.  of  fat  had  been  skimmed  from  it. 

For  methods  of  detection  of  other  adulterations  and 
of  preservatives  in  dairy  products,  see  Chap.  X,  299, 
et  seq. 


Questions. 

1.  What  is  the  weight  of  1000   cc.  of   (a)   water;    (b)    skim 
milk;    (c)    whole  milk;    (d)    cream  testing  30%   fat;    (e)   whey; 
(f)  butter  fat?  ^ 

2.  If  the  sp.  gr.   of  a  sample  of  milk   is  1.0325  at  68°   F., 
what  is  the  lactometer  reading  at  60°? 

3.  What  effect  on   the  sp.   gr.  has  1.0%   solids   not  fat  and 
1.0%  fat? 

4.  How  can  the  accuracy  of  a  lactometer  be  tested? 

5.  If  a  sample  of  milk  has  a  sp.  gr.  of  1.032  and  13.0%  sol- 
ids,  what   is   the  sp.  gr.   of   the  milk   solids? 

6.  How     can    (a)     skimmed     milk,     (b)     watered     milk,     (c) 
skimmed  and  watered  milk  be  detected? 

7.  Give  lactometer  readings  and  percentages  of  fat   in  sam- 
ples   showing    (a)    watering,    (b)    skimming,    (c)    watering    and 
skimming. 

8.  If  one  quart  of  water  is  added  to  one  quart  of  milk,  what 
per  cent,  of  water  is  added,  and  what  per  cent,  extraneous  water 
does  the  mixture   contain? 


116  Testing  Milk  and  Its  Products. 

9.  How  many  pounds  of  fat  have  been  removed  from  a  sam- 
ple of  milk  testing  2.6%,  and  what  per  cent,  of  the  fat  was  re- 
moved? 

10.  If   a   sample   of  milk   contains    7.0%    solids   not   fat,   what 
per  cent,  water  was  added  and  how  much  extraneous  water  did 
the  sample   contain? 

11.  What   has   probably   been    done   to    each   of-  the    following 
samples  of  milk,  that   were   found  to   contain    (a)    7.2   per   cent, 
solids  not  fat,  2.6  per  cent,  fat;   (b)  9.0  per  cent,  solids  not  fat, 
2.5  per  cent,  fat;   (c)   6.5  per  cent,  solids  not  fat,  2.4%  fat? 

12.  What  is  the  per  cent,  solids  not  fat  and  what  is  the  con 
dition  of  each   of   the   following  samples   of  milk: 

Per  Cent.  Fat. 

4.0 
2.5 
3.5 
2.5 
2.4 


Lactometer 

Beading. 

(a) 

32 

.0 

at 

58° 

F. 

(b) 

33 

.5 

at 

56° 

F. 

(c) 

30 

.0 

at 

63° 

F. 

(d) 

28 

.0 

at 

54° 

F. 

(e) 

27 

.4 

at 

69° 

F. 

CHAPTER  VII. 
TESTING  THE  ACIDITY  OF  MILK  AND  CREAM. 

128.  Cause  of  acidity  in  milk.     Even  directly  after 
milk  is  drawn  from  the  udder  it  will  be  found  to  have 
an  acid  reaction,  when  phenolphtalein  is  used  as  an  in- 
dicator.1    The  acidity  of  fresh  milk  is  not  due  to  the 
presence  of  free  organic  acids  in  the  milk,  like  lactic 
or  citric  acid,  but  to  acid  phosphates,  and  possibly  also 
in  part  to  free  carbonic  acid  gas  in  the  milk  or  to  the 
acid  reaction  of  casein.    Even  in  case  of  so-called  sweet 
milk,  nearly  fresh  from  the  cow,  a  certain  amount  of 
acidity,  viz.,  on  the  average  about  .07  per  cent.,  is  there- 
fore found.     When  the  milk  is  received  at  the  factory 
it  will  rarely  test  less  than  .10  per  cent,  of  acid,  calcu- 
lated as  lactid  acid;  some  patrons  bring  milk  day  after 
day  that  does  not  test  over  .15  per  cent,  of  acid;  that 
of  others  tests  from  .20  to  .25  per  cent.,  and  some  lots, 
although  very  rarely,  will  test  as  high  as  .3  of  one  per 
cent,  of  acid.     It  has  been  found  that  milk  will  not 
usually  smell  or  taste  sour  or  "turned,"  until  it  con- 
tains .30  to  .35  per  cent,  of  acid. 

129.  The  acidity  in  excess  of  that  found  normally  in 
milk  as  drawn  from  the  udder,  is  due  to  other  causes 
than  those  described.     Bacteriological  examinations  of 
milk  from  different  sources  and  of  milk  of  the  same 
origin  at  different  times  have  shown  that  there  is,  roughly 
speaking,  a  direct  relation  between  the  bacteria  found 

1  Freshly  drawn  milk  shows  an  amphoteric  reaction  to  litmus,  i.  e., 
it  colors  blue  litmus  paper  red,  and  red  litmus  paper  faintly  blue. 


118  Testing  Milk  and  Its  Products. 

in  normal  milk,  and  its  acidity;  the  larger  the  number 
of  bacteria  per  unit  of  milk,  the  higher  is,  in  general, 
the  acidity  of  the  milk.  The  increase  in  the  acidity 
of  milk  on  standing  is  caused  by  the  breaking- 
down  of  milk  sugar  into  lactic,  acid  through  the  activi- 
ties of  acid-forming  bacteria.  Since  the  bacteria  get 
into  the  milk  through  a  lack  of  cleanliness  during  the 
milking,  or  careless  handling  of  the  milk  after  the 
milking,  or  both,  it  follows  that  an  acidity  test  of  new 
milk  will  give  a  good  clue  to  the  care  bestowed  in  hand- 
ling the  milk.  Such  tests  will  show  which  patrons  take 
good  care  of  their  milk  and  which  do  not  wash  their 
cans  clean,  or  their  hands  and  the  udders  of  the  cows 
before  milking,  and  have,  in  general,  dirty  ways  in  milk- 
ing and  caring  for  the  milk.  The  acidity  test  is  always 
higher  in  summer  than  in  winter,  and  is  generally  high 
in  the  case  of  milk  kept  for  more  than  a  day  (Monday 
milk),  or  delivered  after  a  warm,  sultry  day  or  night. 
The  bacteria  have  had  a  good  chance  to  multiply  enor- 
mously in  such  milk,  even  if  it  be  kept  cooled  down  to 
40° -50°  F.,  and  as  a  result  considerable  quantities  of 
lactic  acid  have  been  formed.  The  determination  of  the 
acidity  of  fresh  milk  is  explained  in  detail  below  (143). 
130.  Method  of  testing  acidity.  Methods  of  meas- 
uring the  acidity  or  alkalinity  of  liquids  by  means  of 
certain  chemicals  giving  characteristic  color  reactions  in 
the  presence  of  acid  or  alkaline  solutions  (so-called 
volumetric  methods  of  analysis)  have  been  in  use  for 
many  years  in  chemical  laboratories.  They  were  applied 
to  milk  as  early  as  1872  by  Soxhlet,1  and  the  method 
worked  out  by  Soxhlet  and  Henkel  has  since  been  in 

1  Jour.  f.  prukt.  Ohemle,  1872,  p.  6,  19. 


Testing  the  Acidity  of  Milk  and  Cream.         119 

general  use  by  European  chemists.  They  measured  out 
50  cc.  of  milk  to  which  was  added  2  cc.  of  a  2  per  cent, 
alcoholic  solution  of  phenolphtalein,  and  this  was  ti- 
trated with  a  one-fourth  normal  soda  solution1  (see 
below) .  In  this  country,  Dr.  A.  G.  Manns  in  1890  pub- 
lished the  results  of  work  done  in  the  line  of  testing 
the  acidity  of  milk  and  cream,2  and  the  method  of  pro- 
cedure and  apparatus  proposed  by  him  has  become 
known  under  the  name  of  Manns'  test,  and  is  being 
advertised  as  such  by  dealers  in  dairy  supplies. 

131.  Manns'  test.  The  acid  in  milk  or  cream  is 
measured  by  using  an  alkali  solution  of  certain  strength, 
with  an  indicator  which  shows  by  a  change  of  color  in 
the  milk  when  all  its  acid  has  been  neutralized.  Any  of 
the  alkalies,  soda,  potash,  ammonia,  or  lime  can  be  used 
for  making  the  standard  solution,  but  it  requires  the 
skill  and  apparatus  of  a  chemist  to  prepare  it  of  the 
proper  strength.  A  tenth-normal  solution3  of  caustic 
soda  is  the  alkali  solution  used  most  frequently  in  de- 
termining the  acidity  of  milk,  and  is  the  solution  labeled 
Neutralizer  of  the  Manns'  test. 

1  Fleischmann,  Lehrb.  d.  Milchwirtschaft,  3rd  ed.,  p.  57. 

2  Illinois  experiment  station,  bulletin  9.. 

3  Normal  solutions,  as  a  general  rule,  are  prepared  so  that  one  liter 
shall  contain  the  hydrogen  equivalent  of  the  active  reagent  weighed 
in  grams  (Button).    Caustic  soda  (NaOH)  is  made  up  of  an  atom  each 
of  sodium  (Na),  oxygen  (O),  and  hydrogen  (H);  its  molecular  weight  is 
therefore 

23+16+1=40 

Na  O    H 

A  normal  soda  solution  then  is  made  by  dissolving  40  grams  of 
soda  in  water,  making  up  the  volume  to  1000  cc. ;  a  one-tenth  normal 
solution  will  contain  one-tenth  of  this  amount  of  soda,  or  4  grams  dis- 
solved in  one  liter.  One  cubic  centimeter  of  the  latter  solution  will 
contain  .001  gram  of  soda,  and  will  neutralize  .009  gram  of  lactic  acid. 
The  formula  for  lactic  acid  is  03H6O3  (see  page  00),  and  its  molecular 
weight  is  therefore  3X12+6X1+3X16=90.  A  tenth-normal  solution  of  . 
lactic  acid  contains  9  grams  per  liter,  and  .009  gram  per  cubic  centimeter.  / 


120  Testing  Milk  and  Its  Products. 

The  indicator  used  is  a  solution  of  phenolphtalein,  a 
light  yellowish  powder;  its  compounds  with  alkalies  are 
red,  in  weak  alkaline  solutions  pink  colored,  while  its 
acid  compounds  are  colorless.  The  phenolphtalein  solu- 
tion used  is  prepared  by  dissolving  10  grams  in  300  cc. 
of  90  per  cent,  alcohol  (Mohr). 

132.  In  testing  the  acidity  of  either  milk  or  cream  it 
is  necessary  to  measure  out  with  exactness  the  quantity 
of  liquid  to  be  tested;  Manns  recommended  using  a  50 
cc.  pipette.  This  amount  of  milk  or  cream  is  measured 
into  a  clean  tin,  porcelain  or  glass  cup,  a  few  drops  of 
the  phenolphtalein  solution  are  added,  and  the  Neutral- 
izer  (or  alkali  solution)  is  cautiously  dropped  in  from 
a  burette,  the  point  at  which  the  solution  stands  before 
any  is  drawn  off  being  noted.  By  constant  stirring 
during  this  operation  it  will  be  noticed  that  the  pink 
color  formed  by  the  addition  of  even  a  drop  of  alkali 
solution  will  at  first  entirely  disappear,  but  as  more  and 
more  of  the  acid  in  the  sample  becomes  neutralized,  the 
color  will  disappear  more  slowly,  until  finally  a  point 
is  reached  when  the  pink  color  remains  permanent  for  a 
time.  No  more  alkali  should  be  added  after  the  first 
appearance  of  a  uniform  pink  color  in  the  sample.  This 
color  will  "fade  and  gradually  disappear  again  on  stand- 
ing, owing  to  the  effect  of  the  carbonic  acid  of  the  air, 
to  which  phenolphtalein  is  very  sensitive.  The  amount 
of  the  alkali  solution  used  for  the  test  is  then  obtained 
from  the  reading  on  the  scale  of  the  burette.  The  per 
cent,  of  acid  in  the  sample  is  calculated  by  multiplying 
the  number  of  cc.  of  alkali  solution  used,  by  .009  and 
dividing  the  predict  hy  the  rmilTher  of  eo.  of  the  sample 
tested,  the  quotient  being  multiplied  by  100. 


Testing  the  Acidity  of  MUk  and  Cream.        121 

e.  c.  alkaliX.009   v 

Per  cent.  acidity= —  — rXlOO 

c.  c.  sample  tested 

If  50  cc.  of  cream  required  32  cc.  of  alkali  solution  to 
produce  a  permanent  pink  color,  the  per  cent,  of  acid  in 

the  cream  would   be  32*;OQ9-XlOO=.58  per    cent     A 

50 

part  of  this  calculation  may  be  saved  by  using  a  factor 
for  multiplying  the  number  of  cc.  of  alkali  added  in 
each  test.  This  factor  is  obtained  by  dividing  .009  (the 
number  of  grams  of  lactic  acid  neutralized  by  one  cc. 
of  alkali  solution)  by  the  number  of  cc.  of  sample 
tested,  and  multiplying  the  quotient  by  100.  If  a  50 
cc.  pipette  is  used  for  measuring  the  sample  to  be  tested, 
the  factor  will  be  (.009-=-50)X  100=^.018;  if  a  25  cc. 
pipette  is  used,  the  factor  will  be  (.009-f-25)XlOO= 
.036;  and  if  a  20  cc.  pipette  is  used,  (.009-1-20)  X 100= 
.045  will  be  the  factor  to  be  applied  in  calculating  the 
per  cent,  of  acidity,  the  number  of  cc.  of  alkali  used 
being  in  all  cases  multiplied  by  the  particular  factor 
corresponding  to  the  volume  of  the  sample  tested. 

133.  If  a  Babcock  milk  test  pipette  is  used  for  measr- 
uring  the  milk  or  cream  to  be  tested  for  acidity,  the 
factor  will  be  (.009^-17.6)  XlOO=.051.  This  is  so  nearly 
.05  that  sufficiently  accurate  results  may  be  obtained  by 
simply  dividing  the  number  of  cc.  used  by  two ;  the  re- 
sult will  be  the  tenths  of  per  cent,  of  acid  in  the  sample 
tested,  e.  g.,  if  17.6  cc.  of  cream  required  12  cc.  of  one- 
.tenth  normal  alkali  to  give  a  pink  color,  then  the  per 
cent,  of  acid  is  12-^2=.6  per  cent.  If  one-fifth  normal 
alkali  is  used  for  testing,  the  per  cent,  of  acidity  is 
shown  directly  by  the  number  of  cc.  used  (Vivian).1 

1  Van  Norman  recommends  the  use  of  a  50th  normal  solution  for 
testing  cream  (see  Purdue  exp..sta.,  bull.  104).     37  cc.  of  a  normal  soda 


122 


Testing  Milk  and  Its  Products. 


134.  Manns'  testing    outfit.       The    appa- 
ratus   (see  fig.   41)    and  chemicals  needed  for 
testing   the   acidity   of    milk   or    cream  by   the 
so-called  Manns '  test  include  one  gallon  of  a 
one-tenth   normal   alkali   solution;    four   ounces 
of    an   alcoholic    solution   of   phenolphtalein,   a 
50    cc.    glass   burette   provided    with    a    pinch- 
cock,  a  burette  stand,  and  a  pipette  for  meas- 
uring the  sample.     This  outfit  will  make  about 
100  tests  and  is  sold  for  $5.00.1 

135.  The  alkaline  tablet  test.    Solid 
alkaline  tablets  were  proposed  by  Far- 
rington  in  1894,  as  a  substitute  for  the 
liquid  used  in  the  Manns '  test.2    It  was 
found  possible  to  mix  a  solid  alkali  car- 
bonate  and   coloring  matter,   and   com- 
press the  mixture  into  a  small  tablet, 
which  would  contain  an  exact  amount 
of  alkali.     The  advantage  of  the  tablets 
lies  in  the  fact  that  they  will  keep  far 

better  than  a  standard  alkali  solu- 
tion, and  they  can  be  easily  and 
safely  sent  by  mail;  they  also  re- 
4uire  less  apparatus  and  are  con- 
FlG'tnMtnnt'rattests.used  siderably  cheaper  than  standard 
alkali  solutions;  1000  of  these  tablets,  costing  $2  00,  will 

solution  is  diluted  to  1850  cc.  in  a  two-quart  bottle,  such  as  is  used  for 
mineral  waters.  Each  cc.  of  this  solution  represents  .01  cc.  of  acidity 
when  17.6  cc.  of  cream  is  measured  off.  The  titration  is  made  in  tin' 
usual  manner,  using  phenolphtalein  as  an  indicator. 

1  Devarda's  acidimetcr  (Milch/eitung,  1896,  p.  785)  is  based  on   tin- 
s;nno  principle  as  Manns'  t«ist:  one-tenth  soda  solution  is  added  to  100 
cc.  of  milk    in   :i   glass-stoppered  graduated  flask,  2  cc.  of  a  4  per  cent, 
phenolphtalein  solution  being  used  as  an   indicator.    The  graduations 
on  the  neck  of  the  flask  give  the  "degrees  acidity"  directly. 

2  Illinois  exp, •riinont  station,  bulletin  32,  April,  1894. 


Testing  the  Acidity  of  Milk  and  Cream.        123 


make  about  400  tests.1  Similar  alkaline  tablets  were 
placed  on  the  market  in  Europe  at  about  the  same  time, 
viz.,  Stokes'  Acidity  Pelletts  in  1893,  and  Eichler's 
Saurepillen  (acid  pills)  in  1895.2 

Two  methods  of  using  the  tablets  have  been  proposed, 
one,  for  the  titration  (determination  of  acidity)  of  rip- 
ening cream  in  the  manufacture  of  sour-cream  butter; 
and  the  other,  for  determining  the  approximate  acidity 
of  different  lots  of  apparently 
sweet  milk  or  cream. 

136.  Determination  of  acidity 
in  sour  cream.  The  method  is 
equally  applicable  for  the  deter- 
mination of  the  acidity  of  sour 


(2>y  hndei» 

of  « 

FIG  .  42.    Apparatus  used  for  determining  the  acidity  of  cream  or  milk. 

cream,  sour  milk  and  buttermilk,  but  is  most  frequently 
employed  in  testing  the  acidity  of  ripening  cream,  to 
examine  whether  or  not  the  ripening  process  has 
reached  the  proper  stage  for  churning  the  cream.  The 
apparatus  used  (see  fig.  42)  is  as  follows : 

1  The  tablets  are  sold  by  dealers  in  dairy  supplies. 

2  Milchzeitung,  1895,  pp.  513-16. 


124  Testing  Milk  and  Its  Products. 

1  Babcock  17.6  cc.  pipette. 
1  white  cup. 

100  cc.  graduated  cylinders;  it  is  well  to  provide  two 
or  three  of  these,  although  only  one  is  strictly  necessary. 

137.  Preparation  of  the  solution.     The  tablet  solu- 
tion formerly  used  was  prepared  by  dissolving  five  tab- 
lets in  50  cc.  of  water;  with  20  cc.  of  cream  each  cubic 
centimeter  of  this  solution  represents  .017  per  cent,  of 
acid  (lactic  acid)  in  the  sample  tested.    The  amount  of 
acid  in  a  given  sample  is  then  obtained  by  multiplying 
the  number  of  cubic  centimeters  of  the  tablet  solution 
used,  by  .017. 

138.  According  to  a  suggestion  made  by  Mr.  C.  L. 
Pitch/  the  strength  of  the  solution  was  changed  in  such 
a  manner  that  the  percentages  of  acidity  are  indicated 
directly  by  the  number  of  cubic  centimeters  of  tablet 
solution  used  in  each  test. 

The  17.6  cc.  Babcock  milk  test  pipette  may  be  used 
for  measuring  the  sample  for  acidity  testing,  and  the 
results  read  directly  from  the  graduated  cylinder,  if 
the  tablet  solution  is  prepared  by  taking  one  tablet  for 
every  19.5  cc.  of  water;  five  tablets  are  therefore  dis- 
solved in  97  cc.  of  water. 

139.  As  cream  during  its  ripening  process  under  the 
conditions  present  in  this  country  generally  has  from 
.5  to  ,6  per  cent,  of  acid  before  it  is  ready  to  be  churned, 
a  50  cc.  cylinderful  of  tablet  solution  of  this  strength 
will  not  be  sufficient  to  make  a  test  of  cream  containing 
over  .5  per  cent,  of  acid,  although  it  is  enough  for  test- 

1  Hoard's  Dairyman,  Sept.  8,  1897. 


Testing  the  Acidity  of  Milk  and  Cream.        125 

ing  the  cream  up  to  this  point  during  the  ripening  pro- 
cess. The  acid-testing  outfit  should  therefore  contain  a 
100  cc.  graduated  cylinder,  instead  of  one  of  50  cc.  capa- 
city, so  that  cream  of  any  amount  of  acidity  up  to  1 
per  cent,  can  be  tested.  A  tablet  solution  of  the  strength 
given  has  not  only  the  advantage  over  the  solution  pre- 
viously recommended  (5  tablets  to  50  cc.  of  water)1 
of  showing  the  per  cent,  of  acidity  directly,  without 
tables  or  calculations,  but  being  weaker,  the  unavoid- 
able errors  of  determination  are  decreased  by  its  use. 

Since  a  17.6  cc.  pipette  is  found  in  creameries  and 
dairies  with  the  Babcock  test  outfit,  no  new  apparatus  is 
necessary  for  making  the  acidity  test  in  the  manner 
given. 

140.  The  preparation  of  the  standard  solution  is  as 
follows:  Five  tablets  are  placed  in  the  100  cc.  cylinder 
which  is  filled  to  the  97  cc.  mark  with,  clean  soft  water.2 
The  cylinder  is  tightly  corked,  shaken  and  laid  on  its 
side,  as  the  tablets  dissolve  more  quickly  when  the  cyl- 
inder is  placed  in  this  position  than  when  left  upright 
with  the  tablets  at  the  bottom.  Several  cylinders  con- 
taining the  tablet  solution  may  be  prepared  at  a  time; 
as  scon  as  one  is  emptied,  tablets  and  water  are  again 
added,  and  the  cylinder  is  corked  and  placed  in  a  hori- 
zontal position.  In  this  way  fresh  solutions  ready  for 
testing  are  always  at  hand.  The  cylinder  is  kept  tightly 
corked  while  the  tablets  are  dissolving,  so  that  none  of 

1  Illinois  experiment   station,  bulletin  32;  Wisconsin   experiment 
station,  bulletin  52. 

2  Condensed  steam  or  rain  water  should  be  used,  and  not  hard  or 
alkali  water,  since  the  impurities  in  these  affect  the  strength  of  the 
tablet  solution. 


126  Testing  Milk  and  Its  Products. 

the  liquid  is  lost  by  the  shaking.  It  is  well  to  put  the 
tablets  in  the  cylinder  with  water  at  night;  the  solution 
will  then  be  ready  for  use  in  the  morning.  Excepting 
a  flocculent  residue  of  inert  matter,  " settlings/7  which 
will  not  dissolve,  the  tablets  must  all  disappear  in  the 
solution  before  this  is  used.  The  strength  of  the  tablet 
solution  does  not  change  perceptibly  by  standing,  at 
least  for  one  week.  The  only  precaution  necessary  is 
to  avoid  evaporation  of  the  solution  by  keeping  the  cyl- 
inders tightly  corked.  The  solid  tablets  will  not  change 
if  kept  dry,  any  more  than  dry  salt  changes  by  age. 

141.  Accuracy  of  the  tablets.    The  tablets  have  been 
repeatedly  tested  by  chemists  and  found  to  be  accurate 
and  very  uniform  in  composition.     Tests  made  with  the 
tablets  according  to  the  directions  here  given  can  there- 
fore be  relied  on  as  correct.    The  alkali  solution  is  very 
sensitive,  however,  and  should  not  be  measured  in  a  cyl- 
inder which   has  been  previously  used   for  measuring 
sulfuric  acid,  as  the  smallest  drop  or  film  of  acid  from 
a  dish  or  from  the  operator's  fingers  will  change  the 
standard  strength  of  the  tablet  solution.     Of  late  pow- 
dered  sodium   carbonate   weighed    out   exactly   in   the 
quantity  required  for  making  a  gallon  of  tenth  normal 
solution  has  been  placed  on  the  market;  these  "test  pow- 
ders "  are  cheaper  than  alkaline  tablets  and  when  put 
out  by  a  reliable  firm  are  equally  accurate  as  these. 

142.  Making  the  test.     The  cream  to  be  tested  is 
thoroughly  mixed,  and  17.6  cc.  are  measured  into  the 
cup.     The  pipette  is  rinsed  once  with  water,  and  the 
rinsings  added  to  the  cream  in  the  cup.     A  few  cc.  of 
the  tablet  solution   prepared   as   given   above  are  now 


Testing  the  Acidity  of  Milk  and  Cream.        127 

poured  from  the  cylinder  into  the  cream  and  mixed 
thoroughly  with  it  by  giving  the  cup  a  gentle  rotary 
motion.  The  tablet  solution  is  added  in  small  quanti- 
ties until  a  permanent  pink  color  appears  in  the  sam- 
ple. The  number  of  cc.  of  tablet  solution  which  has 
been  used  to  color  the  cream  is  now  read  off  on  the 
scale  of  the  cylinder. 

In  comparing  the  results  of  one  test  with  another,  the 
same  shade  of  color  should  always  be  adopted.1  The 
most  delicate  point  is  the  first  change  from  pure  white 
or  cream  color  to  a  uniform  pink  which  the  sample 
shows  when  the  acid  contained  therein  has  been  neu- 
tralized. This  shade  of  color  is  easily  recognized  with 
a  little  practice.  The  pink  color  is 'not  permanent  un- 
less a  large  excess  of  the  alkaline  solution  has  been 
added,  on  account  of  the  influence  of  the  carbonic  acid 
of  the  air  (132),  and  the  operator  should  not  therefore 
be  led  to  believe  by  the  reappearance  of  the  white  color 
after  a  time,  that  the  point  of  neutralization  was  not 
already  reached  when  the  first  uniform  shade  of  pink 
was  observed. 

143.  Acidity  of  cream.  17.6  cc.  of  sweet  cream  is 
generally  neutralized  by  15  to  20  cc.  of  this  tablet  solu- 
tion, representing  from  .15  to  .20  per  cent,  of  acid.  A 
mildly  sour  cream  is  colored  by  35  cc.  tablet  solution,  and 
a  sour  cream  ready  for  churning  by  about  50  to  60  cc. 

1  A  helpful  suggestion  has  been  made  by  the  Danish  State  Dairy  In- 
structor, Dr.  G.  Ellbrecht,  for  obtaining  a  uniform  color  in  all  acidity 
tests.  Strips  of  pink  paper  are  attached  to  the  cup  or  glass  in  which 
the  titration  is  made,  and  alkali  solution  is  added,  until  the  color  of  the 
milk  or  cream  corresponds  to  that  of  the  strips. 


128  Testing  Milk  and  Its  Products. 

tablet  solution.  As  the  cream  ripens,  its  acidity  in- 
creases. The  rate  of  ripening  depends  largely  on  the 
temperature  at  which  the  cream  is  kept.  Cream  con- 
taining .5  to  .6  per  cent,  of  acid  will  make  such  butter 
as  our  American  market  demands  at  the  present  time. 
Cream  showing  an  acid  test  of  .55  per  cent,  may  not  be 
too  sour,  but  .65  per  cent,  of  acid  is  very  near,  if  not 
on  the  danger  line,  since  such  cream  is  likely  to  make 
strong  flavored,  almost  rancid  butter.  Each  lot  of  cream 
should  be  tested  as  soon  as  it  is  ready  for  ripening,  and 
the  result  of  the  test  will  show  whether  the  cream  should 
be  warmed  or  cooled  in  order  to  have  it  ready  for  churn- 
ing at  the  time  desired.  Later  tests  will  show  the  rate 
at  which  the  ripening  is  progressing,  and  the  time  when 
the  cream  has  reached  the  proper  acidity  for  churning. 
144.  The  influence  of  the  richness  of  cream  on  the 
acid  test  has  been  studied  by  Professor  Spillman,1  and 
others.2  Since  the  acidity  develops  in  the  cream  serum, 
it  follows  that  an  acidity  of,  say  .5  per  cent,  in  a  40 
per  cent,  cream  represents  a  larger  acidity  than  in  20 
per  cent,  of  cream,  e.  g. ;  in  the  former  case  we  have  .5 
gram  of  acid  in  60  grams  of  serum  (=.83  per  cent,  of 
the  serum)  ;  in  the  latter  case  .5  gram  acid  is  found  in 
80  grams  serum  (=.63  per  cent,  of  the  serum).  There- 
fore, rich  cream  need  not  be  ripened  to  as  high  a  degree 
of  acidity  as  thin  cream.  A  table  is  given  in  the  Iowa 
bulletin  referred  to,  showing  the  relation  between  the 
richness  and  the  acidity  of  cream. 

1  Washington  experiment  station,  bulletin  :$!?. 

2  Chicago  Dairy  Produce,  April  '21, 1(.KX),  p.  80;  Town   <>.\pt.  stn.,  bull.  5*2. 


Testing  the  Acidity  of  Milk  and  Cream.        129 


(45.  Spillman's  cylinder.  The  graduated  cylinder  shown  in 
fig.  43  was  devised  by  Professor  Spillman  for  use  in  testing  the 
acidity  of  milk  and  cream  with  Farrington's  alkaline  tablets. 
The  following  directions  are  given  for  making 
tests  with  this  piece  of  apparatus:1 

"All  that  is  needed  in  addition  to  the  acid-test 
graduate  shown  in  the  accompanying  illustration, 
is  a  common  prescription  bottle  of  six  or  eight 
ounce  capacity,  and  a  package  of  Farrington's 
alkaline  tablets.  Fill  the  bottle  with  water  and 
add  one  tablet  for  each  ounce  of  water  in  the 
bottle.  Shake  the  bottle  frequently  to  aid  in  dis- 
solving, the  tablets. 

"Making  the  test.  In  making  the  test,  the 
acid-test  graduate  is  filled  to  the  zero  mark  with 
the  milk  or  cream  to  be  tested.  The  tablet  solu- 
tion is  then  added,  a  little  at  a  time,  and  the 
graduate  shaken  after  each  addition,  in  order  to 
t  thoroughly  mix  the  milk  and  the  tablet  solution. 

In  snaking  the  graduate,  give  it  a  rotary  motion 
FIG.  43.    Spill-  .  .,,.  „    ..       ,.       .»   • ,  Vi 

man's  cylinder,  to    prevent   spilling   any   of   the  liquid.      Continue 

mfifln^theaclci-  adding  tne  tablet  solution  until  a  permanent  pink 
ity  of  cream  or  color  can  be  detected  in  the  milk.  The  level  of 
the  liquid  in  the  graduate,  measured  by  the  scale 
on  the  graduate,  will  then  show  the  per  cent,  of  the  acidity  of  the 
milk.  It  is  best  to  stand  the  graduate  on  a  piece  of  white  paper, 
so  that  the  first  pink  coloration  of  the  milk  may  be  easily  de- 
tected. ' ' 

146.  The  Marschall  acid  test  (see  fig.  44)  is  a  con- 
venient apparatus  for  determining  the  acidity  of  milk, 
cream,  or  whey.2  It  is  used  with  tenth-normal  alkaline 
solution  ("Nentralizer"),  9  cc.  of  milk,  cream,  etc., 
being  measured  out  for  the  test,  and  alkali  solution 
added  from  the  combined  burette  and  bottle,  the  former 
being  graduated  to  two-tenths  of  one  cc.  With  the 

1  Washington  experiment  station,  bulletin  24. 

2  See  Wis.  exp.  sta.  bull.  129. 

9 


130  Testing  Milk  and  Its  Products. 

quantity  of  milk  given,  the  readings  obtained  represent 
per  cent,  of  acidity  direct. 

147.  Rapid  estimation  of  the  acidity  of  apparently 
sweet  milk  or  cream,  a,  Milk.  The  alkaline  tablet 
method  offers  a  ready  means  of  estimating  the  acidity 
of  milk  or  cream  that 
is  still  sweet  to  the 
taste.  The  selection  of 
the  best  kinds  of  milk 
is  especially  important 
in  pasteurizing  milk 
or  cream.  As  pre- 
viously noted,  milk 
which  gives  the  high- 
est acid  test  contains, 
as  a  rule,  a  larger 
number  of  bacteria 
and  spores  not  de- 
stroyed by  pasteuriza- 
tion than  does  milk 
giving  a  low  acid  test 
(129)  ;  the  acidity  test 
may  therefore  be  used 

to    advantage   for   the         FIG"  44'  T^  Mamchaii  add  test, 
purpose  of  selecting  milk  best  adapted  for  pasteuriza- 
tion, as  well  as  such  as  is  to  be  retailed  or  used  in  the 
manufacture  of  high-grade  butter  and  cheese. 

In  distinguishing  milk  fit  for  pasteurization  purposes 
from  that  which  is  doubtful,  an  arbitrary  standard  of 
two-tenths  of  one  per  cent,  of  acid  may  be  taken  as  the 


Testing  the  Acidity  of  Milk  and  Cream.        131 


upper  limit  for  milk  of  the  former  kind.  The  appara- 
tus used  in  making  this  test  is  shown  in  the  accompany- 
ing illustration  (fig.  45),  and  consists  of  a  white  tea- 
cup; a  four-,  six-,  or  eight-ounce  bottle,  and  a  No.  10 
brass  cartridge  shell,  or  a  similar  measure.  A  solution 
of  the  tablets  in  water  is  first  prepared,  one  tablet  being 
always  added  to  each  ounce  of  water:  four  tablets  in  a 


k  "Measure 


FIG.  45.  Apparatus  used  for  rapid  estimation  of  the  acidity  of  ap- 
parently sweet  milk  or  cream. 

four-ounce  bottle;  six,  in  a  six-ounce  bottle,  etc.,  the 
amount  of  tablet  solution  prepared  depending  on  the 
number  of  tests  to  be  made  at  a  time.  The  bottle  is  filled 
up  to  its  neck  with  clean,  soft  water,  and  the  solution 
prepared  in  the  manner  previously  given  (140). 

148.  Operating  the  test.  As  each  lot  of  milk  is 
brought  to  the  creamery  in  the  morning  and  poured  into 
the  weigh  can,  a  cartridge-shell  dipper  is  filled  with 


132  Testing  Milk  and  Its  Products. 

milk  and  this  is  poured  into  the  white  cup.  The  same  or 
another  No.  10  shell  is  now  filled  twice  with  the  the  tab- 
let solution  and  emptied  into  the  milk  in  the  cup.  In- 
stead of  dipping  twice  with  one  measure  or  a  No.  10 
shell,  a  tin  measure  can  be  made  holding  as  much  as  two 
No.  10  shells,  or  the  tablet  solution  may  be  made  of 
double  strength ;  that  is,  two  tablets  to  each  ounce  of 
water  and  the  same  sized  measure  used  for  both  the  milk 
and  the  tablet  solution.  The  liquids  are  then  mixed  in 
the  cup  by  giving  this  a  quick,  rotary  motion,  and  the 
color  of  the  mixture  noticed.  If  the  milk  remains  white 
it  contains  more  than  two-tenths  of  one  per  cent,  of  acid 
and  should  not  be  used  for  pasteurization.  If  it  is  col- 
ored after  having  been  thoroughly  mixed  with  two 
measures  of  tablet  solution,  it  contains  less  than  this 
amount  of  acid  and  may,  as  far  as  acidity  goes,  be  safely 
used  for  pasteurization  or  for  any  other  purpose  which 
requires  thoroughly  sweet  milk.  The  shade  of  color  ob- 
tained will  vary  with  different  lots  of  milk;  the  sweet- 
est milk  will  be  most  highly  colored,  but  a  milk  retain- 
ing even  a  faint  pink  color  with  two  measures  of  tablet 
solution,  or  one  measure  of  the  double  strength  solution 
to  one  measure  of  milk,  contains  less  than  .2  per  cent, 
of  acid. 

By  proceeding  in  the  manner  described,  the  man  re- 
ceiving and  inspecting  the  milk  at  the  factory  weigh-can  * 
is  able  to  test  the  acidity  of  the  milk  delivered  nearly  as 
quickly  as  he  can  weigh  it ;  and  according  to  the  results 
of  the  test  he  can  send  the  milk  to  the  general  delivery 
vat  or  to  the  pasteurization  vat,  as  the  weigh-can  may 
be  provided  with  two  conductor  spouts. 


Testing  the  Purity  of  Milk.  133 

149.  Size  of  measure  necessary.     It  is  not  necessary 
to  use  a  No.  10  shell  for  a  measure  in  working  the  pre- 
ceding method;  one  of  any  convenient  size  that  can  be 
filled  accurately  and  quickly,  will  answer  the  purpose 
equally  well,  if  a  measure  of  the  same  size  is  used  for 
both  the  sample  and  the  tablet  solution.    Each  measure- 
ful  of  tablet  solution  made  up  as  directed,  will  in  this 
case  represent  one-tenth  per  cent,  of  acid  in  the  sam- 
ple tested.1 

150.  b,  Cream.     Cream  can  be  tested  in  the  way  al- 
ready described  for  testing  the  acidity  of  fresh  milk,  by 
adding  to  one  measureful  of  cream  in  the  cup  as  many 
measures  of  tablet  solution  as  are  necessary  to  change 
the  color  of  the  cream  when  the  two  liquids  are  thor- 
oughly mixed.     If  one  measure  of  tablet  solution  colors 
one  measure  of  cream,  this  contains  less  than  .1  per 
cent,  acid;  if  five  measures  of  tablet  solution  are  re- 
quired, the  cream  contains  about  .5  per  cent,  acid,  etc. 
By  proceeding  in  the  manner  described,  the  operator 
can  estimate  the  acidity  to  within  .05  per  cent,  of  acid, 
if  half  measures  of  tablet  solution  are  added.     The  re- 
sults thus  obtained  are  sufficiently  delicate  for  all  prac- 
tical purposes. 

151.   Detection  of  boracic-acid  preservatives  in  milk.    The 

application  of  the  alkaline  tablet  test  for  detecting  boracic  acid  in 
milk  was  first  discussed  in  bulletin  No.  52  of  Wisconsin  experi- 
ment station.  The  acidity  of  the  milk  is  increased  by  the  addi- 
tion of  boracic  acid,  but  neither  the  odor  nor  the  taste  of  the 
milk  is  affected  thereby.  By  adding  to  sweet  milk  the  amount 

1  In  European  creameries  and  city  milk  depots  the  alcohol  test  is 
often  applied  to  every  can  of  milk  received;  milk  that  is  sufficiently 
sour  to  be  noticed  by  the  taste,  will  coagulate  when  mixed  with  an 
equal  volume  of  70%  alcohol. 


134  Testing  Milk  and  Its  Products. 

of  boracic  acid  which  will  keep  it  sweet  36  hours,  its  acidity  may 
be  increased  to  .35  per  cent.,  in  a  sample  of  milk  which  pre- 
viously tested  perhaps  only  .15  per  cent.  acid. 

As  before  stated,  unadulterated  milk  will  usually  smell  or 
taste  sour  or  "  turned, "  when  it  contains  .30-. 35  per  cent,  acid 
(121)  •  milk  testing  as  high  as  this  limit,  which  neither  smells 
nor  tastes  sour  in  any  way,  is  therefore  in  all  probability  adul- 
terated with  some  preparation  containing  boracic  acid  or  a  simi- 
lar compound. 

152.  "Alkaline  tabs."  These  are  not  the  alkaline  tablets, 
but  a  substitute  which  was  put  on  the  market  by  a  New  York 
firm.  The  outfit  furnished  consisted  of  four  packages  of  paper 
discs  made  of  filter  paper,  each  of  about  the  size  of  an  old-style 
copper  cent;  two  packages  of  square  paper;  one  glass  of  about 
10  cc.  capacity,  and  one  small  glass  bottle.  An  investigation  of 
these  "Tabs"  soon  disclosed  the  fact  that  they  were  entirely 
inaccurate,  and  that  no  dependence  could  therefore  be  placed  on 
the  results  obtained  by  their  use. 

Questions. 

1.  What  is   the   meaning  of   a  one-tenth  normal   alkali   solu- 
tion? 

2.  How    are   the   results   expressed   in   testing   cream  by   the 
Manns7  test? 

3.  What  per  cent,  acidity  is  indicated  by  35  cc.  &  alkali? 

4.  If  20  cc.  cream  require  12  cc.  *T*J    alkali  for  neutralization, 
what  per  cent,  acid  in  the  sample? 

5.  If  1  cc.    NJ  alkali  neutralize  .009  gram  lactic  acid,  what  is 
the  per  cent,  of  acid  in  a  sample  of  cream,  which  required  12  cc. 
alkali  for  25  cc.  of  cream? 

6.  What   apparatus   and   strength  of   solution   must  be   taken 
to  show  per  cent,  acidity  directly  from  cc.  alkali  used  with  Far- 
rington's  alkaline  tablets? 

7.  If  cream  testing  20%  fat  has  an  acidity  of  .6%,  what  will 
be  the  corresponding  acidity  of  cream  testing  40%  fat? 

8.  Describe  the  rapid  method  of  testing  acidity  of  samples  of 
milk  or  cream  by  the  alkaline  tablet  solution. 

9.  What  is  the   per   cent,   acidity   in   a  sample   that  requires 
2  oz.  of  standard  tablet  solution  to  give  a  pink  color  in  1  oz.  of 
milk? 


CHAPTER  VIII. 
TESTING  THE   PURITY  OF  MILK. 

153.  The  Wisconsin  curd  test.     Cheese  makers  are 
often  troubled  with  so-called  floating   or   gassy   curds 
which  produce  cheese  defective  in  flavor  and  texture. 
These  faults  are  usually  caused  by  some  particular  lot 
of  milk  containing  impurities  that  cannot  be  detected 
by  ordinary  means  of  inspection.     The  Wisconsin  curd 
test  is  used  to  detect  the  source  of  these  defects  and 
thus  enable  the  cheese  maker  to  exclude  the  milk  from 
the  particular  farm   or   cow  to   which  the   trouble   is 
traced.     This  test  is  similar  in  principle  to  tests  that 
have  for  many  years  past  been  in  use  in  cheese-making 
districts  in  Europe,  notably  in  Switzerland,1  but  was 
worked    out    independently    at    the    Wisconsin    Dairy 
School  in  1895  and  is  now  generally  known  as  the  "Wis- 
consin Curd  Test."2 

154.  Method  of  making  the  test.     Pint  glass  jars, 
thoroughly  cleaned  and  sterilized  with  live  steam,  are 
provided;  they  are  plainly  numbered   or  tagged,   one 
jar  being  provided  for  each  lot  of  milk  to  be  tested.  The 
jars  are  filled  about  two-thirds  full  with  milk  from  the 
various  sources;  it  is  not  necessary  to  take  an  exact 

*  Herz,  Unters.  d.  Kuhmilch,  Berlin,  1889,  p.  87;  Slats,  Unters. 
landw.  wicht.  Stoffe,  1903,  p.  140. 

2  Wisconsin  experiment  station,  twelfth  report,  p.  148.  The  appar- 
atus used  for  the  test  was  greatly  improved  in  1898,  and  a  description 
of  the  improved  test  is  given  in  bulletin  No.  67  and  the  annual  report 
of  the  Station  for  1898  (fifteenth  report,  p.  47-53),  from  which  source  the 
accompanying  illustration  is  taken  (see  fig.  46). 


136 


Testing  Milk  and  Its  Products. 


quantity;  they  are  then  placed  in  a  water  tank,  the 
water  of  which  is  he'ated  until  the  milk  in  the  jars  has 
a  temperature  of  98°  F.  In  transferring  the  thermom- 
eter used  from  one  jar  to  another,  special  care  must  be 
taken  to  clean  it  each  time  in  order  to  prevent  contami- 
nation of  pure  lots  of  milk  by  impure  ones. 

When  the  milk  has  reached  a  temperature  of  98°, 
add  to  each  sample  ten  drops  of  rennet  extract,  and  mix 
by  giving  the  jar  a  rotary  motion.  The  milk  is  thus 
curdled,  and  the  curd  allowed  to  stand  for  about  twenty 


FIG.  46.  Gross-section  of  the  Wisconsin  curd  test.  T  J-TJ",  testing 
jars  showing  different  stages  of  test ;  WL,  water  line ;  M,  milk ;  F,  frame ; 
WS,  stand  to  support  cover;  AI,  drain  holes;  WO,  water  outlet;  hi'- 
drain  pail. 

minutes  until  it  is  firm.  It  is  then  cut  fine  with  a  case 
knife,  and  stirred  at  intervals  for  one-half  to  three- 
quarters  of  an  hour  sufficiently  to  keep  the  curd  from 
matting  under  the  whey.  When  the  cubes  are  quite  firm 
the  whey  is  poured  off  and  the  curd  left  to  mat  at  the 
bottom  of  the  bottles  if  the  old  form  of  apparatus  is 
used.  The  best  tests  are  made  when  the  separation  of 
the  whey  is  most  complete.  By  allowing  the  samples  to 
stand  for  a  short  time,  more  whey  can  be  poured  off, 
and  the  curd  thereby  rendered  firmer.  The  water  around 
the  jars  is  kept  at  a  temperature  of  98°,  the  vat  is  cov- 
ered, and  the  curds  allowed  to  ferment  in  the  sample 
jars  for  six  to  twelve  hours. 


Testing  the 

During  this  time  the 
sample  will  cause  gases  to  be  develop 6(1  ill  tluTcurds  so 
that  by  examining  these,  by  smelling  of  them  and  cut- 
ting them  with  a  sharp  knife,  those  having  a  bad  flavor, 
or  a  spongy  or  in  any  way  abnormal  texture  may  be 
easily  detected,  and  thus  traced  to  the  milk  causing  the 
trouble. 

Since  the  curd  test  was  first  described,  several  modi- 
fications have  been  made  in  the  apparatus.  In  one  of 
these  the  bottles  are  held  in  a  covered  metal  frame  so 
that  all  of  them  can  be  drained  at  once  by  inverting  the 
frame. 

155.  By  proceeding  in  the  way  described  with  the 
milk  from  the  different  cows  in  a  herd,  the  mixed  milk 
of  which  produced  abnormal  curds,  the  source  of  con- 
tamination in  the  herd  may  be  located.  Very  often  the 
trouble  will  be  found  to  come  from  the  cows'  drinking 
foul  stagnant  water  or  from  fermenting  matter  in  the 
stable.  In  the  former  case  the  pond  or  marsh  must  be 
fenced  off,  or  the  cows  kept  away  from  it  in  other  ways ; 
in  the  latter,  a  thorough  cleaning  and  disinfection  of 
the  premises  are  required.  If  the  milk  of  a  single  cow 
is  the  source  of  contamination,  it  must  be  kept  by  itself, 
until  the  milk  is  again  normal;  under  such  conditions 
the  milk  from  the  healthy  cows  may,  of  course,  safely 
be  sent  to  the  factory. 

156.  The  fermentation  test.  The  Gerber  fermentation 
test  (see  fig.  47)  also  furnishes  a  convenient  method  for 
examining  the  purity  of  different  lots  of  milk.  The  test  consists 
of  a  tin  tank  which  can  be  heated  by  means  of  a  small  lamp, 


138 


Testing  Milk  and  Its  Products. 


and  into  which  a  rack  fits,  holding  a  certain  number  of  cylin- 
drical glass  tubes;  these  are  all  numbered  and  provided  with  a 
mark  and  a  tin  cover. 
In  making  the  test,  the 
tubes  are  filled  to  the 
mark  with  milk,  the  num- 
ber of  each  tube  being 
recorded  in  a  note  book, 
opposite  the  name  of  the 
particular  patron  whose 
milk  was  placed  therein. 
The  tubes  in  the  rack  are 
put  in  the  tank,  which  is 
two-thirds  full  of  water;  FlG-  47-  The  Gerber  fermentation  test, 
the  temperature  of  the  water  is  kept  at  104-106°  F.,  for 
six  hours,  when  the  rack  is  taken  out,  the  tubes  gently  shaken, 
and  the  appearance  of  the  milk,  its  odor,  taste,  etc.,  carefully 
noted  in  each  case. 

The  tubes  are  then  again  heated  in  the  tank  at  the  same  tem- 
perature as  before,  for  another  six  hours,  when  observations  of 
the  appearence  of  the  milk  in  each  tube  are  once  more  taken.  The 
tainted  milk  may  then  easily  be  discovered  by  the  abnormal 
coagulation  of  the  sample.  According  to  Gerber,1  good  and  prop- 
erly handled  milk  should  not  coagulate  in  less  than  twelve  hours, 
when  kept  under  the  conditions  described,  nor  show  anything 
abnormal  when  coagulated.  Milk  from  sick  cows  and  from  cows 
in  heat,  or  with  diseased  udders,  will  always  coagulate  in  less 
than  twelve  hours.  If  the  milk  does  not  curdle  within  a  day  or 
two,  it  should  be  tested  for  preservatives  (299). 

157.  The  Monrad  rennet  test  is  used  by  cheese  mak- 
ers for  determining  the  ripeness  of  milk.  Fig.  48  shows 
the  apparatus  used  in  the  test.  5  cc.  of  rennet  extract 
is  measured  into  a  50  cc.  flask  by  means  of  a  pipette; 
the  pipette  is  rinsed  with  water,  and  the  flask  filled  to 
the  mark  with  water.  160  cc.  of  milk  is  now  measured 
into  the  tin  basin  from  the  cylinder  and  slowly  heated 
to  exactly  86°  F.  5  cc.  of  the  dilute  rennet  solution  is 


Die  praktische  Milchpriifung,  p.  85. 


Testing  the  Purity  of  Milk. 


139 


quickly  added  to  the  warm  milk  and  the  time 
rfequired  for  coagulation 
noted.1  Milk  sufficiently  ripe 
for  cheddar  cheese  making 
will  coagulate  in  30  to  60 
seconds,  according  to  the 
strength  of  the  rennet  ex- 
tract used. 

158.  The  Marschall  ren- 
net test  is  used  for  the  same 
purpose  as  the  Monrad  test. 
The  directions  for  this  test 
are  as  follows :  Fill  the  small 
glass  with  pure  water  to 
the  mark,  pour  into  it  one 
cc.  of  rennet  extract  and 
rinse  the  pipette  in  the  same 

FIG.  48.   The  Monrad  rennet  test.  water<       Fm      ^      cup     ^^ 

•milk  to  the  zero  mark,  add  the  rennet,  mix  thoroughly 
and  allow  it  to  stand.  The  sweeter  the  milk  is,  the 
longer  it  will  take  to 
coagulate,  and  the  more 
milk  will  run  out  of  the 
cup  before  the  point  of 
coagulation  is  reached, 
when  the  flow  of  milk 
will  cease.  The  time  re- 
quired for  coagulating  tj 
the  milk  is  shown  di-  ^ 

rectly  by  a  Scale  On  the     FIG-  49-    Tne  Marsphall  rennet  test. 

inside  wall  of  the  cup  (see  fig.  49). 

1  Decker,  Cheese  Making,  1900,  p.  36. 


CHAPTER  IX. 
TESTING  MILK  ON  THE  FARM. 

159.  Variations  in  milk  of  single  cows.     The  varia- 
tions in  the  tests  of  milk  of  single  cows  from  milking  to 
milking  or  from   day  to  day,  are   greater  than  many 
cow-owners  suspect.     There  seems  to  be  no  uniformity 
in  this  variation,  except  that  the  quality  of  the  milk 
produced  generally  improves  with  the  progress  of  .the 
period  of  lactation;   even  this  may  not  be  noticeable, 
however,  except  when  the  averages  of  a  number  of  tests 
made  at  different  stages  during  the  lactation  period  are 
compared  with  each  other.    When  a  cow  gives  her  maxi- 
mum quantity  of  milk,  shortly  after  calving,  the  qual- 
ity of  her  milk  is  generally  poorer  (by  one  per  cent,  of 
fat  or  less)    than  when  she  is  drying  off.     Strippers' 
milk  is  therefore,  as  a  rule,  richer  in  fat  than  the  milk 
of  fresh  cows. 

160.  By  testing  separately  every  milking  of  a  number 
of  cows  through  their  whole   period  of  lactation,   the 
results  obtained  have  seemed  to  warrant  the  following 
conclusions  in  regard  to  the  variations  in  the  test  of  tbo 
milk  from  single  cows,  and  it  is  believed  that  these  con- 
clusions allow  of  generalization.1 

1.  Some  cows  yield  milk  that  tests  about  the  same  at 
every  milking,  and  generally  give  a  uniform  (jiinntity 
of  milk  from  day  to  day. 

1  Illinois  experiment  station,  bulletin  sM. 


Testing  Milk  on  the  Farm.  141 

2.  Other  cows  give  milk  that  varies  in  an  unexplain- 
able  way  from   one   milking  to   another.     Neither  the 
morning  nor  the  evening  milking  is  always  the  richer, 
and  even  if  the  interval  between  the  two  milkings  is 
exactly  the  same,  the  quality  as  well  as  the  quantity  of 
milk  produced  will  vary  considerably.     Such  cows  are 
generally  of  a  nervous,  excitable  temperament,  and  are 
easily  affected  by  changes  in  feed,  drink,  or  surround- 
ing conditions. 

3.  The  milk  of  a  sick  cow,  or  of  a  cow  in  heat,  as  a 
rule,  tests  higher  than  when  the  cow  is  in  normal  con- 
dition; the  milk  yield  generally  decreases  under  such 
conditions;  marked  exceptions  to  this  rule  have,  how- 
ever, been  observed. 

4.  Half-starved  or  underfed  cows  may  give  a  small 
yield  of  milk  testing  higher  than  when  the  cows   are 
properly  nourished,  probably  on  account  of  an  accom- 
panying feverish  condition  of  the  animal.    The  milk  is, 
however,  more  generally  of  an  abnormally  low  fat  con- 
tent, which  may  be  readily  increased  to  the  normal  per 
cent,  of  fat  by  liberal  feeding. 

5.  Fat  is  the  most  variable  constituent  of  milk,  while 
the  solids   not  fat  vary   within  comparatively  narrow 
limits.    The  summary  of  the  analyses  of  more  than  2400 
samples  of  American  milk  calculated  by  Cooke1  shows 
that  while  the  fat  content  varies  from  3.07  to  6.00  per 
cent.,  that  of  casein  and  albumen  varies  only  from  2.92 
to  4.30  per  cent.,  or  less  than  one  and  one-half  per  cent., 

1  Vermont  experiment  station,  report  for  1890,  p.  97. 


142  Testing  Milk  and  Its  Products. 

and  the  milk  sugar  and  ash  content  increases  but  little 
(about  .69  per  cent.)  within  the  range  given. 

6.  A  test  of  only  one  milking  may  give  a  very  erro- 
neous impression  of  the  average  quality  of  a  certain 
cow's  milk.  A  composite  sample  (see  179)  taken  from 
four  or  more  successive  milkings  will  represent  the 
average  quality  of  the  milk  which  a  cow  produces  at 
the  time  of  sampling. 

161.  The  variations  that  may  occur  in  testing  the 
milk  of  single  cows,  are  illustrated  by  the  following  fig- 
ures obtained  in  an  experiment  made  at  the  Illinois  ex- 
periment station,1  in  which  the  milk  of  each  of  six  cows 
was  weighed  and  analyzed  daily  during  the  whole  period 
of  lactation.  Among  the  cows  were  pure-bred  Jerseys, 
Shorthorns  and  Holsteins,  the  cows  being  from  three  to 
eight  years  of  age  and  varying  in  weight  from  850  to 
1350  Ibs.  During  a  period  of  two  months  of  the  year, 
the  cows  were  fed  a  heavy  grain  ration  consisting  of 
twelve  Ibs.  of  corn  and  cob  meal,  six  Ibs.  of  wheat  bran, 
and  six  Ibs.  of  linseed  meal,  per  day  per  head.  This  sys- 
tem of  feeding  was  tried  for  the  purpose  of  increasing, 
if  possible,  the  richness  of  the  milk.  The  influence  of  this 
heavy  grain  feed,  as  well  as  that  of  the  first  pasture 
grass  feed,  on  the  quality  and  the  quantity  of  the  milk 
produced  is  shown  in  the  following  table,  which  gives 
the  complete  average  data  for  one  of  the  cows  (No.  3). 
The  records  of  the  other  cows  are  given  in  the  publica- 
tion referred  to ;  they  were  similar  to  the  one  here  given 
in  so  far  as  variations  in  quality  are  concerned. 

1  Bulletin  24. 


Testing  Milk  on  the  Farm. 


143 


Average  results  obtained  in  weighing  and  testing  a  cow's 
milk  daily  during  one  period  of  lactation. 


MONTH 

3S 
P 

Daily  milk 
yield 

Test  of  one  day's 
milk 

Yield  of  fat  per 
day 

<D 

8  «J 

> 

w 

16.0 
17.7 
17.7 
16.0 
16.5 
17.2 
14.0 
12.2 
9.3 

+3 

03 

r 

|l 

o>"o 

is' 
°l 

9 

L 

00 

<t> 

W 

1   . 

r 

.34 

.44 
.51 

.50 
.46 
.44 
.35 

.27 
.16 

December.  . 
January  .... 
February.  .. 
March  
April  . 

920 
927 
1035 
1047 
1054 
1079 
1105 
1180 
1130 

12.1 
16.0 
16.1 
14.3 
13.8 
14.5 
12.1 
9.3 
6.4 

10.0 
14.0 
13.5 
12.5 
11.5 
10.0 
9.2 
6.0 
3.5 

3.8 
3.7 
3.6 
3.8 
4.0 
3.8 
3.9 
4.2 
4.7 

4.9 
4.6 

5.8 
4.7 
5.8 
4.6 
4.6 
6  2 
7.9 

3.0 

2.7 
3.2 
3.4 
3.0 
3.4 
3.2 
2.8 
2.9 

.46 
.59 
.58 
.54 
.55 
.55 
.47 
.39 
.30 

.60 
.76 

.84 
.61 
.72 

157 
.60 
.50 

May  
June  
July. 

August  

162.  The  average  test  of  this  cow's  milk  for  her  whole 
period  of  lactation  was  3.8  per  cent,  of  fat  (i.  e.,  the 
total  quantity  of  fat  produced  -4-  total  milk  yield  X 
100)  ;  twice  during  this  time  the  milk  of  the  cow  tested 
as  high  as  5.8  per  cent.,  and  once  as  low  as  2.7  per  cent. 
The  average  weight  of  milk  produced  per  day  by  the 
cow  was  14  Ibs. ;  this  multiplied  by  her  average  test, 
3.8,  shows  that  she  produced  on  the  average  .53  lb.,  or 
about  one-half  of  a  pound,  of  butter  fat  per  day  during 
her  lactation  period.  If,  however,  her  butter-producing 
capacity  had  been  judged  by  the  test  of  her  milk  for 
one  day  only,  this  test  might  have  been  made  either  on 
the  day  when  her  milk  tested  5.8  per  cent.,  or  when  it 
was  as  low  as  2.7  per  cent.  Both  of  these  tests  were 
made  in  mid-winter  when  the  cow  gave  about  16  Ibs.  of 
milk  a  day.  Multiplying  this  quantity  by  .058  gives  .93 
lb.  of  fat,  and  by  .027  gives  .43  lb.  of  fat.  Either 


144  Testing  Milk  and  Its  Products. 

result  would  show  the  butter  fat  produced  by  the  cow  on 
certain  days,  but  neither  gives  a  correct  record  of  her 
actual  average  daily  performance  for  this  lactation 
period. 

A  sufficient  number  and  variety  of  tests  of  the  milk 
of  many  cows  have  been  made  to  prove  that  there  is 
no  definite  regularity  in  the  daily  variations  in  the 
richness  of  the  milk  of  single  cows.  The  only  change  in 
the  quality  of  milk  common  to  all  cows  is,  as  stated, 
the  natural  increase  in  fat  content  as  the  cows  are  dry- 
ing off,  and  even  in  this  case  the  improvement  in  the 
quality  of  the  milk  sometimes  does  not  occur  until  the 
milk  yield  has  dwindled  down  very  materially. 

163.  Causes  of  variations  in  fat  content.   The  qual- 
ity of  a  cow's  milk  is,  as  a  rule,  decidedly  influenced  by 
the  following  conditions: 

Length  of  interval  between  milkings. 

Change  cf  feed. 

Change  of  milkers. 

Rapidity  of  milking. 

Exposure  to  rain  or  bad  weather. 

Rough  treatment. 

Unusual  excitement  or  sickness. 

164.  Disturbances   like   those   enumerated   frequently 
increase  the  richness  of  the  milk   for  one,   and  some- 
times for  several  milkings,  but  a  decrease  in  quality  fol- 
lows during  the  gradual  return  to  normal  conditions, 
and  taken  as  a  whole  there  is  a  considerable  falling  off 
in  the  total  production  of  milk  and  butter  fat  by  the 
cow,  on  account  of  the  nervous  excitement  which  she 
has  gone  through.     Aside  from   changes   due  to  well- 


Testing  Milk  on  the  Farm.  145 

definable  causes  like  those  given  above,  the  quality  of 
some  cows'  milk  will  often  change  considerably  without 
any  apparent  cause.  The  dairyman  who  is  in  the  habit 
of  making  tests  of  the  milk  of  his  individual  cows  at 
regular  intervals  will  have  abundant  material  for  study 
in  the  results  obtained,  and  he  will  soon  be  able  to  tell 
from  the  tests  made,  if  these  are  continued  for  several 
days,  whether  or  not  the  cows  are  in  a  normal  healthy 
condition  or  have  been  subjected  to  excitement  or  abuse 
in  any  way. 

165.  Number  of  tests  required  during  a  period  of 
lactation  in  testing  cows.     The  daily  records  of  the 
six  cows  referred  to  on  page  142  furnish  data  for  com- 
paring their  total  production  of  milk  and  butter  fat  dur- 
ing one  period  of  lactation,  as  found  from  the  daily 
weights  and  tests  of  their  milk,  with  the  total  amount 
calculated  from  weights  and  tests  made  at  intervals  of 
7,  10,  15  or  30  days.     The  averages  of  all  results  ob- 
tained with  each  of  the  six  cows  show  that  weighing  and 
testing  the  milk  of  a  cow  every  seventh  day  gave  98  per 
cent,  of  the  total  milk  and  butter  fat,  which  according 
to  her  daily  record  was  the  total  product.     Tests  made 
once  in  two  weeks  gave  97.6  per  cent,  of  the  total  milk, 
and  98.5  per  cent,  of  the  total  butter  fat,  and  tests  made 
once  a  month,  or  only  ten  times  during  the  period  of 
lactation,  gave  96.4  per  cent,  of  the  total  milk,  and  97 
per  cent,  of  the  total  production  of  butter  fat. 

166.  The  record  of  one  of  the  cows  will  show  how 
these  calculations   are  made:     It  was  found  from  the 
daily  weights  and  tests  that  cow  No.  1,  in  one  lactation 

period  of  307  days,  gave  5,044  Ibs.  of  milk  which  con- 
10 


146 


Testing  Milk  and  Its  Products. 


tained  254  Ibs.  of  butter  fat.  Selecting  every  thirtieth 
day  of  her  record  as  testing  day,  the  total  production  of 
milk  and  fat  is  shown  to  be  as  follows: 

Production  of  milk  and  butter  fat  per  day. 


Testing  day 

Weight  of  Milk 

Test  of  Milk" 

Yield  of  butter  fat 

Nov.     4 

R>8. 

20  5 

per  cent. 

4  7 

Ibs. 
96 

Dec.      4  

18  7 

4  6 

86 

Jan.      3   

17.7 

4  9 

86 

Feb.      2  

20.0 

4  5 

90 

Mar.      3 

18  2 

4  7 

86 

April    2  

19  5 

4  4 

81 

May      2  

17.7 

4  8 

85 

June     1  

13.1 

5  5 

72 

July      1  

12.2 

6.2 

76 

July    31  .  . 

3  2 

7  2 

23 

Total  

160.8  Ibs. 

7  81  Ibs. 

Average  per  day. 

16.08  Ibs. 

4.85 

.78  ft). 

The  average  daily  production  of  the  cow,  according 
to  the  figures  given  in  the  preceding  table,  was  about 
16  Ibs.  of  milk,  containing  .78  Ib.  of  butter  fat.  Multi- 
plying these  figures  by  307,  the  number  of  days  during 
which  the  cow  was  milked,  gives  4,912  Ibs.  of  milk  and 
240  Ibs.  of  fat.  This  is  132  Ibs.  of  milk  and  14  Ibs.  of 
fat  less  than  the  total  weights  of  milk  and  butter  fat,  as 
found  by  the  daily  weights  and  tests,  or  2.8  and  5.5  per 
cent,  less,  for  milk-  and  fat  production,  respectively. 
This  is,  however,  calculated  from  only  ten  single  weights 
and  tests,  while  it  required  over  600  weighings  and  300 
tests  of  the  milk  to  obtain  the  exact  amount. 

Similar  calculations  from  the  records  of  the  other 
cows  gave  fully  as  close  results,  showing  that  quite  sat- 


Testing  Milk  on  the  Farm.  147 

is  factory  data  as  to  the  total  production  of  milk  and 
butter  fat  of  a  cow  may  be  obtained  by  making  correct 
weighings  and  tests  of  her  full  day's  milk  once  every 
thirty  days. 

167.  When  to  test  a  cow.  The  Vermont  experi- 
ment station  for  several  years  made  a  special  study  of 
the  question  when  a  cow  should  be  tested  in  order  to 
give  a  correct  idea  of  the  whole  year's  production,  when 
only  one  or  two  tests  are  to  be  made  during  the  lacta- 
tion period.1  The  results  obtained  may  be  briefly  sum- 
marized as  follows: 

a.  As  to  quality  of  milk  produced.  If  two  tests  of 
each  cow  ?s  milk  are  to  be  made  during  the  same  lacta- 
tion period,  it  is  recommended  to  take  composite  sam- 
ples at  the  intervals  given  below. 


KIKST  S  A  MPLS 

SEC''    N       1AX  t'LK 

For  spring 

For  summer     •  ' 
For  fall            " 

ks  after  calving 

0                 41                  44                        <( 

8-10" 

6J-71  mos.  after  calving 
6-7 
5J-7      •'         "         " 

If  only  one  test  is  to  be  made,  approximately  correct 
-   Its  may  be  obtained  by  testing  the  milk  during  the 
h  month  from  calving,  in  case  of  spring  cows ;  dur- 
ing the  third  to  fifth  month  in  case  of  summer-calving 
3,  and  during  the  fifth  to  seventh  month  for  fall- 
calving  cows. 

In  all  cases  composite  samples  of  the  milk  for  at  least 
four  days  should  be  taken  (169).  "The  test  of  a  single 
sample,  drawn  from  a  single  milking  or  day,  will  not  of 
necessity,  or  indeed  usually,  give  trustworthy  results." 

1  Sixth  report,  1S81>.  p.  lOtf:  Ninth  report.  1886,  p.  17& 


148  Testing  Milk  and  Its  Products. 

b.  As  to  quantity  of  milk  produced.  The  milk  may 
be  weighed  for  four  days  in  the  middle  of  the  month, 
and  the  entire  month's  yield  obtained  with  considerable 
accuracy  (barring  sickness  and  drying  off), 
by  multiplying  the  sum  by  7,  iy2  or  7%, 
according  to  the  number  of  days  in  the  dif- 
ferent months.  The  weighing  is  most  read- 
ily done  by  means  of  a  spring  balance,  the 
hand  of  which  is  set  back  so  that  the  empty 
pail  brings  it  to  zero  (fig.  50).  If  several 
pails  are  to  be  used,  they  should  first  be 
made  to  weigh  the  same  by  putting  a  little 
solder  on  the  lighter  pails.  Milk  scales 
which  weigh  and  automatically  register  the 
yield  of  milk  from  twenty  cows  have  been 
placed  on  the  market,  but  so  far  as  known 
FlG'ScaieMllk  have  not  proved  satisfactory.1 

168.  Sampling  milk  of  single  cows.  In  sampling 
the  milk,  of  single  cows,  all  the  milk  obtained  at  the 
milking  must  be  carefully  mixed,  by  pouring  it  from 
one  vessel  to  another  a  few  times,  or  stirring  it  thor- 
oughly by  means  of  a  dipper  moved  up  and  down,  as 
well  as  horizontally,  in  the  pail  or  can  in  which  it  is 
held;  a  sample  for  testing  purposes  is  then  taken  at 
once.  A  correct  sample  of  a  cow's  milk  cannot  be  ob- 
tained by  milking  directly  into  a  small  bottle  from  one 

1  The  various  state  experiment  stations  now  conduct  official  /r.v/.v  of 
dairy  cows  for  breeders  and  dairy  fiirmors,  by  which  the  production  of 
milk  and  butter  fat  by  cows  is  determined  accurately  by  representa- 
tives of  the  stations.  Information  concerning  these  tests  may  be  had 
by  writing  to  the  director  of  the  nearest  experiment  station. 


Testing  Mttk  on  the  Farm.  149 

teat,  or  by  filling  the  bottle  with  a  little  milk  from  each 
teat,  or  by  taking  some  of  the  first,  middle  and  last  milk 
drawn  from  the  udder.  Such  samples  cannot  possibly 
represent  the  average  quality  of  the  milk  of  one  entire 
milking,  since  there  is  as  much  difference  between  the 
first  and  the  last  portions  of  a  milking,  as  between  milk 
and  cream.1  Lack  of  care  in  taking  a  fair  sample  is 
the  cause  of  many  surprising  results  obtained  in  testing 
the  milk  of  single  cows. 

169.  Composite  samples.  When  a  cow  is  to  be  tested, 
she  should  be  milked  dry  the  last  milking  previous  to 
the  day  when  the  test  is  to  be  made.  The  entire  quan- 
tity of  milk  obtained  at  each  milking  is  mixed  and 
sampled  separately.  On  account  of  the  variation  in  the 
composition  of  the  milk,  a  number  of  tests  of  successive 
milkings  must  be  made.  As  this  involves  considerable 
labor,  the  plan  of  taking  composite  samples  is  prefer- 
able; the  method  of  composite  sampling  and  testing  is 
explained  in  detail  under  the  second  subdivision  of 
Chapter  X  (180)  ;  suffice  it  here  to  say  that  the  method 
followed  in  the  case  of  single  cow's  or  herd  milk  is  to 
take  about  an  ounce  of  the  thoroughly  mixed  milk  of 
each  milking;  this  is  placed  in  a  pint  or  quart  glass  jar 
containing  a  small  quantity  of  some  preservative,  prefer- 
ably about  one-half  a  gram  (8  grains)  of  powdered 
potassium  bi-chromate.  If  a  number  of  composite  sam- 
ples of  the  milk  of  single  cows  are  taken,  each  jar  should 
be  labeled  with  the  number  or  name  of  the  particular 

1  Woll,  Handbook  for  Farmers  and  Dairymen,  p.  249;  Agricultural 
Science,  6,  pp.  540-42. 


150  Testing  Milk  and  Its  Products. 

cow.  Composite  tests  are  generally  taken  for  four  days 
or  for  a  week.  If  continued  for  a  week,  the  jars  will 
contain  at  the  end  of  this  time  a  mixture  of  the  milk 
of  fourteen  milkings.  The  composite  sample  is  then 
carefully  mixed  by  pouring  it  gently  a  few  times  from 
one  jar  to  another,  and  is  tested  in  the  ordinary  man- 
ner. The  result  of  this  test  shows  the  average  quality 
of  the  milk  produced  by  the  cow  during  the  time  the 
milk  was  sampled. 

As  the  amounts  as  well  as  the  quality  of  the  milk  pro- 
duced by  single  cows  vary  somewhat  from  day  to  day 
and  from  milking  to  milking,  it  is  desirable  in  testing 
single  cows,  especially  when  the  test  includes  only  a  few 
days,  to  take  a  proportionate  part  (an  aliquot)  of  each 
milking  for  the  composite  test  sample.  This  is  easily 
done  by  means  of  a  Scovell  sampling  tube,  the  use  of 
which  is  explained  in  another  place  (183),  or  by  a  25  cc. 
pipette  divided  into  -fa  cc. ;  in  using  the  latter  appara- 
tus as  many  cubic  centimeters  and  tenths  of  a  cubic 
centimeter  of  milk  are  conveniently  taken  each  time  for 
the  composite  sample  as  the  weight  of  milk  in  pounds 
and  tenths  of  a  pound  produced  by  the  cow.1 

170.  The  opinion  is  sometimes  expressed  that  a  con- 
siderable error  is  introduced  by  measuring  out  milk 
warm  from  the  cow  for  the  Babcock  test,  since  milk  ex- 
pands on  being  warmed,  and  a  too  small  quantity  is 
obtained  in  this  manner.  By  calculation  of  the  expan- 
sion of  milk  between  different  temperatures  it  is  found 
that  1  cc.  of  milk  at  17.5°  C.  (room  temperature)  will 

i  Decker,  Wls.  experiment  station,  report  XVI,  155. 


Testing  Milk  on  the  Farm.  151 

have  a  volume  of  1.006289  cc.  at  37°  C.  (blood-heat), 
i.  e.,  an  error  of  less  than  .03  per  cent,  is  introduced  by 
measuring  out  milk  of  ordinary  quality  at  the  latter 
temperature.  While  the  temperature  has  therefore  prac- 
tically no  importance,  the  air  incorporated  in  the  milk 
during  the  milking  process  will  introduce  an  appreci- 
able error  in  the  testing,  and  samples  of  milk  should 
therefore  be  left  for  an  hour  or  more  after  milking  be- 
fore the  milk  is  measured  into  the  test  bottles.  By  this 
time  the  specific  gravity  of  the  samples  can  also  be  cor- 
rectly determined  (113). 

171.  Size  of  the  testing  sample.     Four  ounces  is  a 
sufficient  quantity  for  a  sample  of  milk  if  it  is  desired 
to  determine  its  per  cent,  of  fat  only ;  if  the  milk  is  to 
be  tested  with  a  lactometer,  when  adulteration  is  sus- 
pected, a  pint  sample  is  needed.     If  this  sample  of  milk 
is  put  into  a  bottle  and  carried  or  sent  away  from  the 
farm  to  be  tested,  the  bottle  should  be  filled  with  milk 
clear  up  to  the  neck  to  prevent  a  partial  churning  of 
butter  in  the  sample  during  transportation  (30). 

172.  Variations   in  herd   milk.     While  considerable 
variations  in  the  quality  of  the  milk  of  single  cows  are 
often  met  with,  a  mixture  of  the  milk  of  several  cows, 
or  of  a  whole  herd,  is  comparatively  uniform  from  day 
to  day;  the  individual  differences  tend  to  balance  each 
other  so  that  variations,  when  they  do  occur,  are  less 
marked  than  in  case  of  milk  of  single  cows.    There  are, 
however,  at  times  marked  variations  also  in  the  test  of 
herd  milk  on  successive  days ;  the  following  figures  from 
the  dairy  tests  conducted  at  the  World's  Columbian  Ex- 
position in  Chicago  in  1893  illustrate  the  correctness  of 


152 


Testing  Milk  and  Its  Products. 


this  statement.  The  tests  included  twenty-five  Jersey 
and  Guernesey  cows  each  and  twenty-four  Shorthorn 
cows. 

Tests  of  herd  milk  on  successive  days. 


DATE 

Jersey 

Guernsey 

Shorthorn 

July  16,  1893.. 

4  8  per  cent 

4  6  per  cent 

3  8  per  cent 

July  17,  1893  

5.0 

45        " 

38        " 

July  18,  1893  

4.7        " 

4.4        " 

38        " 

Jnly  19,  1893  

4.6 

4.6 

37 

July  20,  1893 

50 

45 

38        " 

On  July  17,  1893,  the  mixed  milk  of  the  Jersey  cows 
tested  two-tenths  of  one  per  cent,  higher  than  on  the 
preceding  day ;  the  Guernsey  herd  milk  tested  one-tenth 
of  one  per  cent,  lower,  while  the  Shorthorn  milk  did  not 
change  in  composition;  comparing  the  tests  on  July  19 
and  20,  we  find  that  the  Jersey  and  Shorthorn  milk 
tested  four-tenths  and  one-tenth  of  one  per  cent,  higher, 
respectively,  on  the  latter  day  than  on  the  former,  and 
the  Guernsey  milk  tested  one-tenth  of  one  per  cent, 
lower. 

173.  Ranges  in  variations  of  herd  milk.  According 
to  Fleischmann,1  the  composition  of  herd  milk  may  on 
single  days  vary  from  the  average  values  for  the  year, 
expressed  in  per  cent,  of  the  latter,  as  follows: 

The  specific  gravity  (expressed  in  degrees)  may  go  above  or 
below  the  yearly  average  by  more  than  10  per  cent. 

The  per  cent,  of  fat  may  go  above  or  below  the  yearly  aver- 
age by  more  than  30  per  cent. 

The  per  cent,  of  total  solids  may  go  above  or  below  the  yearly 
average  by  more  than  14  per  cent. 

1  Book  of  the  Dairy,  p.  32.' 


Testing  Milk  on  the  Farm.  153 

The  per  cent,  of  solids  not  fat  may  go  above  or  below  the 
yearly  average  by  more  than  10  per  cent. 

To  illustrate,  if  the  average  test  of  a  herd  during  a  whole 
period  of  lactation  is  4.0  per  cent.,  the  test  on  a  single  day  may 
exceed  4.0+30  X  4.0=5.2,  or  may  go  below  2.8  per  cent,  (viz., 
4.0 —  so  X4.0)  ;  if  thei  average  specific  gravity  is  1.031  (lacto- 
meter degrees,  31  )J  the  specific  gravity  of  the  milk  on  a  single 
day  may  vary  between  1.0279  and  1.0341  (31+^X31=34.1; 
31-^X31=27.9). 

174.  Influence  of  heavy  grain-feeding  on  the  qual- 
ity of  milk.    If  cows  are  not  half-starved  or  underfed, 
an  increase  in  the  feeding  ration  will  not  materially 
change  the  richness  of  the  milk  produced,  as  has  been 
shown  by  numerous  careful  feeding  experiments  con- 
ducted under  a  great  variety  of  conditions  and  in  many 
countries.     Good  dairy  cows  will  almost  invariably  give 
more  milk  when  their  rations  are  increased,  so  long  as 
they  are  not  overfed,  but  the  milk  will  remain  of  about 
the  same  quality  after  the  first  few  days  are  passed  as 
before  this  time,  provided  the  cows  are  in  good  health 
and  under  normal  conditions.     Any  change  in  the  feed 
of  cows  will  usually  bring  about  an  immediate  change 
in  the  fat  content  of  the  milk,  as  a  rule  increasing  it  to 
some  extent,  but  in  the  course  of  a  few  days,  when  the 
cows  have  become  accustomed  to  their  new  feed,  the  fat 
content  will  again  return  to  its  normal  amount. 

175.  The  records  of  the  cows  included  in  the  feeding 
experiment  at  the   Illinois  station,  to  which  reference 
has  been  made  on  p.  142,  furnish  illustrations  as  to  the 
effect  of  heavy  feeding  on  the  quality  of  milk.     The 
feed,  as  well  as  the  milk  of  the  cows,  was  weighed  each 
day  of  the  experiment.    During  the  month  of  December 

i  See  page  101. 


154  Testing  Milk  and  Its  Products. 

each  cow  was  fed  a  daily  ration  consisting  of  10  Ibs.  of 
timothy  hay,  20  Ibs.  of  corn  silage  and  2  Ibs.  of  oil  meal ; 
the  table  on  p.  143  shows  that  cow  No.  3  produced  on 
this  feed  an  average  of  12.1  Ibs.  of  milk,  testing  3.8  per 
cent,  of  fat.  In  January  the  grain  feed  was  gradually 
increased  until  the  ration  consisted  of  12  Ibs.  of  timothy 
hay,  8  Ibs.  of  corn  and  cob  meal,  4  Ibs.  of  wheat  bran, 
and  4  Ibs.  of  oil  meal.  All  the  cows  gained  in  milk  on 
this  feed ;  cow  No.  3  thus  gave  an  average  of  4  Ibs.  more 
milk  per  day  in  January  than  in  December,  but  the 
average  test  of  her  milk  was  3.7  per  cent.,  or  one-tenth 
of  one  per  cent,  lower  than  during  the  preceding  month. 
The  heavy  grain-feeding  was  continued  through  Febru- 
ary and  March,  when  it  reached  12  Ibs.  of  timothy  hay, 
12  Ibs.  of  corn  and  cob  meal,  6  Ibs.  of  wheat  bran  and 
6  Ibs.  of  oil  meal  per  day.  The  records  show  that  the 
flow  of  milk  kept  up  to  16  Ibs.  per  day  in  February  in 
case  of  this  cow,  but  fell  to  14  Ibs.  in  March  and  April, 
the  average  test  of  the  milk  being,  in  February  3.6,  in 
March  3.8,  and  in  April  4.0  per  cent.  The  milk  was, 
therefore,  somewhat  richer  in  April  than  in  December, 
but  not  more  so  than  is  found  normally,  owing  to  the 
progress  of  the  period  of  lactation. 

176.  Influence  of  pasture  on  the  quality  of  milk. 
On  May  1,  the  cows  were  given  luxuriant  pasture  feed 
and  no  grain ;  a  slight  increase  in  the  average  amount  of 
milk  produced  per  day  followed,  with  a  reduction  in 
the  test,  this  being  3.8  per  cent.,  the  same  as  in  De- 
cember. 

During  all  these  changes  of  feed  there  was,  therefore, 
not  much  change  in  the  richness  of  the  milk,  while  the 


Testing  Milk  on  the  Farm.  155 

flow  of  milk  was  increased  by  the  heavy  grain  feeding 
for  several  months,  as  well  as  by  the  change  from  grain- 
feeding  in  the  barn  to  pasture  feed  with  no  grain.1  As 
a  general  rule,  the  test  of  the  milk  will  be  increased  by 
a  few  tenths  of  a  per  cent,  during  the  first  couple  of 
weeks  after  the  cows  have  been  turned  out  to  pasture 
in  the  spring.  The  increase  is  perhaps  due  as  much  to 
the  stimulating  influence  of  out-door  life  after  the  con- 
finement in  the  stable  during  the  winter  and  spring,  as 
to  the  change  in  the  feed  of  the  cows.  After  a  brief 
period  the  milk  will  again  change  back  to  its  normal  fat 
content. 

177.  The  increase  which  has  often  been  observed  in 
the  amount  of  butter  produced  by  a  cow,  as  a  result  of 
a  change  in  feed,  doubtless  as  a  rule  comes  from  the 
fact  that  more,  but  not  richer  milk  is  produced.  The 
quality  of  milk  which  a  cow  produces  is  as  natural  to 
her  as  is  the  color  of  her  hair  and  is  not  materially 
changed  by  any  special  system  of  normal  feeding.2 

*  For  further  data  on  this  point,  see  Cornell  (N.  Y.)  exp.  sta.,  bulle- 
tins 13,  22,  36  and  49;  N.  D.  exp  sta.,  bull.  16;  Kansas  exp.  sta.,  report, 
1888;  Hoard's  Dairyman,  1896,  pp.  924-5,  W.  Va.  exp.  sta.,  b.  109. 

2  On  this  point  numerous  discussions  have  in  recent  years  taken 
place  in  the  agricultural  press  of  this  and  foreign  countries,  and  the 
subject  has  been  under  debate  at  nearly  every  gathering  of  farmers 
where  feeding  problems  have  been  considered.  Many  farmers  are  firm 
in  their  belief  that  butter  fat  can  be  "fed  into"  the  milk  of  a  cow,  and 
would  take  exception  to  the  conclusion  drawn  in  the  preceding.  The 
results  of  careful  investigations  by  our  best  dairy  authorities  point  con- 
clusively, however,  in  the  direction  stated,  and  the  evidence  on  this 
point  is  overwhelmingly  against  the  opinion  that  the  fat  content  of  the 
milk  can  be  materially  and  for  any  length  of  time  increased  by  changes 
in  the  system  of  feeding.  The  most  conclusive  evidence  in  this  line  is 
perhaps  the  Danish  co-operative  cow-feeding  experiments,  conducted 
during  the  nineties  with  over  2,000  cows  in  all.  The  conclusion  arrived 
at  by  the  Copenhagen  experiment  station,  uuder  whose  supervision  the 
experiments  have  been  conducted,  is:  that  the  changes  of  feed  made  in 


156  Testing  Milk  and  Its  Products. 

178.  Method   of    improving    the   quality   of     milk. 

The  quality  of  the  milk  produced  by  a  herd  can  gener- 
ally be  improved  by  selection  and  breeding,  i.  e.,  by  dis- 
posing of  the  cows  giving  poor  milk,  say  below  3  per 
cent,  of  fat,  and  by  breeding  to  a  pure-bred  bull  of  a 
strain  that  is  known  to  produce  rich  milk.  This  method 
cannot  work  wonders  in  a  day,  or  even  in  a  year,  but  it 
•  is  the  only  certain  way  we  have  of  improving  the  qual- 
ity of  the  milk  produced  by  our  cows. 

It  may  be  well  in  this  connection  to  call  attention  to 
the  fact  that  the  quality  of  the  milk  which  a  cow  pro- 
duces is  only  one  side  of  the  question;  the  quantity  is 
another,  and  an  equally  important  one.  Much  less  dis- 
satisfaction and  grumbling  about  low  tests  among  pat- 
rons of  creameries  and  cheese  factories  would  arise  if 
this  fact  was  more  generally  kept  in  mind.  A  cow  giv- 
ing 3  per  cent,  milk  should  not  be  condemned  because 
her  milk  does  not  test  5  per  cent. ;  she  may  give  twice 
as  much  milk  per  day  as  a  5  per  cent  cow,  and  will 
therefore  produce  considerably  more  butter  fat.  The 
point  whether  or  not  a  cow  is  a  persistent  milker  is  also 
of  primary  importance ;  a  production  of  300  Ibs.  of  but- 
ter fat  during  a  whole  period  of  lactation  is  a  rather 
high  dairy  standard,  but  one  reached  by  many  herds, 
even  as  the  average  for  all  mature  cows  in  the  herd. 

the  different  lots  of  cows  included  on  the  experiments  had  prm-t  it-ally 
no  influence  on  the  chemical  composition  (the  fat  content)  of  the  milk 
produced.  In  these  experiments  grain  feeds  were  fed  against  roots, 
against  oil  cake,  and  against  wheat  bran  or  shorts;  trnmi  ;md  oil  rak<- 
were  furthermore  fed  against  roots,  and  roots  wen-  yivcn  as  nn  addi- 
tional feed  to  the  standard  rations  tried,— in  all  cases  with  prm-t ically 
negative  results  so  far  as  changes  in  the  fat  contents  of  the  milk  pro- 
duced are  concerned. 


Testing  Milk  on  the  Farm.  157 

It  should  be  remembered  that  a  high  production  of  but- 
ter fat  in  the  course  of  the  whole  period  of  lactation  is 
of  more  importance  than  a  very  high  test. 


1.  How  does  the  test  of  the  milk  yielded  by  a  cow  generally 
change  with  the  advance  of  the.  period  of  lactation? 

2.  Mention  at  least  six  causes  of  variations  in  the  test  of  a 
cow's  milk. 

3.  How  is  an  accurate  sample  taken  of  a  cow's  milk? 

4.  Between   which   limits   is   the   test  of   milk   of   single   cows 
and  of  a  herd  likely  to  vary? 

5.  Will  it  introduce  any  error  in  the!  test  of  a  cow's  milk  to 
measure  out  the  sample  directly  after  milking  ?If  so,  how  much? 

6.  How  many  times  should  the  milk  of  a  cow  be  weighed  and 
tested   to   calculate!  the   total   production  of   milk   and  butter   fat 
by  the  cow  during  a  whole  period  of  lactation? 

7.  What  is  an  official  test  of  a  cow? 

8.  How   does   the   test,   as   a  general  rule,   change   during   the 
first  couple  of  wc^eks  after  the  cows  are  let  out  on  pasture  in  the 
the  spring? 

9.  How  do  changes  in  the  feed  of  a  cow  influence  the  quan- 
tity and  the  quality  of  her  milk? 


CHAPTER  X. 


COMPOSITE  SAMPLES  OF  MILK. 

179.  Shortly  after  milk  testing  had  been  introduced 
to  some  extent  in  creameries  and  cheese  factories,  it  was 
suggested  by  Patrick,  then  of  the  Iowa  experiment  sta- 
tion,1 that  a  great  saving  in  labor,  without  affecting 

the  accuracy  of  the 
results,  could  be  ob- 
tained by  testing  a 
mixture  of  the  daily 
samples  of  milk  from 
one  source,  instead  of 
each  one  of  these 
samples.  Such  a  mix- 
ture is  called  a  com- 
posite sample.  The 
usual  methods  of  tak- 
ing such  samples  at 
creameries  and  cheese 
factories  are  as  fol- 
lows: 

180.    Methods     of 
taking   composite 

FIG.  51.    Taking  test  samples  at  in-take.       samples.      a.    Use    of 

tin  dipper.  Either  pint  or  quart  fruit  jars,  or  milk  bot- 
tles provided  with  a  cover,  are  used  for  receiving  the 
daily  samples.  One  of  these  jars  is  supplied  for  each 

l  Bulletin  9.  May  1890. 


Composite  Samples  of  Milk.  159 

patron  of  the  factory  and  is  labeled  with  his  name  or 
number.  A  small  quantity  of  preservative  (bi-chromate 
of  potash,  corrosive  sublimate,  etc.,  see  190)  is  added  to 
each  jar;  these  are  placed  on  shelves  or  somewhere 
within  easy  reach  of  the  operator  who  inspects  and 
weighs  the  milk  as  it  is  received  at  the  factory.  When 
all  the  milk  delivered  by  a  patron  is  poured  into  the 
weighing  can  and  weighed,  a  small  portion  thereof, 
usually  about  an  ounce,  is  put  into  the  jar  labeled  with 
the  name  or  number  of  the  patron.  The  samples  are 
conveniently  taken  by  means  of  a  small  tin  dipper  hold- 
ing >about  an  ounce.  This  sampling  is  continued  for  a 
week,  ten  days,  or  sometimes  two  weeks,  a  portion  of 
each  patron's  milk  being  added  to  his  particular  jar 
every  time  he  delivers  milk.  A  test  of  these  composite 
samples  takes  the  place  of  separate  daily  tests  and  gives 
accurate  information  regarding  the  average  quality  of 
the  milk  delivered  by  each  patron  during  the  period  of 
sampling.  The  weight  of  butter  fat  which  each  patron 
brought  to  the  factory  in  his  milk  during  this  time,  is 
obtained  by  multiplying  the  total  weight  of  milk  deliv- 
ered during  the  sampling  period  by  the  test  of  the  com- 
posite sample,  dividing  the  product  by  100. 

181.  This  method  of  taking  composite  samples  has 
been  proved  to  be  practically  correct.  It  is  absolutely 
correct  only  when  the  same  weight  of  milk  is  delivered 
daily  by  the  patron.  If  this  is  not  the  case,  the  size  of 
the  various  small  samples  should  bear  a  definite  relation 
to  the  milk  delivered;  one  sixteen-hundredth,  or  one 
two-thousandth  of  the  amount  of  milk  furnished  should, 
for  instance,  be  taken  for  the  composite  sample  from 


160  Testing  Milk  and  Its  Products. 

each  lot  of  milk.  This  can  easily  be  done  by  means  of 
special  sampling  devices  (see  182  et  seq.).  As  the  quan- 
tities of  the  milk  delivered  from  day  to  day  by  each 
patron  vary  but  little,  perhaps  not  exceeding  10  per 
cent,  of  the  milk  delivered,  the  error  introduced  by 
taking  a  uniform  sample,  e.  g.,  an  ounce  of  milk,  each 
time  is,  however,  small  and  it  may  not  be  necessary  to 
take  cognizance  of  it  in  factory  work.  This  method  of 
composite  sampling  described  is  quite  generally  adopted 
in  separator  creameries  and  cheese  factories,  where  the 
payment  for  the  milk  is  based  on  its  quality. 

In  order  to  obtain  reliable  results  by  composite  sam- 
pling it  is  essential  that  each  lot  of  milk  sampled  shall 
be  sweet  and  in  good  condition,  containing  no  lumps  of 
curdled  milk  or  butter  granules.  The  milk  should  of 
course  always  be  evenly  mixed  before  the  sample  is 
taken. 

182.  b.  Drip  sample.  Composite  samples  are  some- 
times taken  at  creameries  and  cheese  factories  by  col- 
lecting in  a  small  dish  the  milk  that,  drips  through  a 
fine  hole  in  the  bottom  of  the  conductor  spout  through 
which  the  milk  runs  from  the  weighing  can  to  the  re- 
ceiving vat  or  tank.  A  small  portion  of  the  drip  col- 
lected each  day  is  placed  in  the  composite  sample  jar, 
or  the  quantity  of  drip  is  regulated  so  that  all  of  it 
may  be  taken.  In  the  latter  case  the  quantity  of  milk 
delivered  will  enter  into  the  composite  sampling  as  well 
as  its  quality  and  the  sample  from,  say  200  Ibs.  of  milk, 
will  be  twice  as  large  as  the  sample  from  100  Ibs.  of  milk. 

Where  it  is  desired  to  vary  the  size  of  samples  accord- 
ing to  the  quantity  of  milk  delivered  from  day  to  day. 


Composite  Samples  of  Milk.  161 

it  is  necessary  to  adopt  the  method  of  collecting  drip 
samples,  just  explained,  or  to  make  use  of  special  sam- 
pling devices,  like  the  "milk  thief,"  the  Scovell,  Equity, 
McKay,  and  Michels  sampling  tubes.1  The 
principle  of  these  tubes  is  the  same,  and  it  will 
be  sufficient  to  describe  here  only  a  few  of  them. 
183.  c.  The  Scovell  sampling  tube.  This 
convenient  device  for  sampling  milk2  (fig.  52) 
consists  of  a  drawn  copper  or  brass  tube,  one- 
half  to  one  inch  in  diameter;  it  is  open  at  both 
ends,  the  lower  end  sliding  snugly  in  a  cap  pro- 
vided with  three  elliptical  openings  at  the  side, 
through  which  the  milk  is  admitted.  The  milk 
to  be  sampled  is  poured  into  a  cylindrical  pail, 
or  the  factory  weighing  can,  and  the  tube,  with 
the  cap  set  so  that  the  apertures  are  left  open, 
is  lowered  into  the  milk  until  it  touches  the 
bottom  of  the  can.  The  tube  will  be  filled  in- 
stantly to  the  level  of  the  milk  in  the  can  and 
is  then  pushed  down  against  the  bottom  of  the 
can,  thereby  closing  the  apertures  of  the  cap 
FIG.  52.  and  confining  within  the  tube  a  column  of  milk 

SCOVel 

milk     representing    exactly   the   quality    of   the   milk 

sampling 

tube,  in  the  can  and  forming  an  aliquot  part  thereof. 
The  milk  in  the  sampling  tube  is  then  emptied  into  the 
composite  sample  jar  by  turning  the  tube  upside  down. 

1  A  recent  Wisconsin   law  (Chap.  99,  laws  of  1907)   provides  that  in 
sampling  cream  or  milk  from  which  composite  tests  arc  to  be  made  to 
determine  the  per  cent  of  butter  fat  therein,  no  such  sampling  shall  be 
lawful,  unless  a  sample  be  taken  from  each  weighing,  and  the  quantity 
thus  used  shall  be  proportioned  to  the  total  weight  of  cream  or  milk 
tested. 

2  Kentucky  experiment  station,  8th  report,  pp.  xxvi-xxvii. 

11 


162  Testing  Milk  and  Its  Products. 

184.  If  the  diameter  of  the  sampling  pail  used  is  8 
inches,  and  that  of  the  sampling  tube  ^  inch,  the  quan- 
tity of  milk  secured  in  the  tube  will  always  stand  in  the 
ratio  to  that  of  the  milk  in  the  pail,  of   (1/2) 2  to  82,1 
that  is,  as  1  to  256,  no  matter  how  much  or  how  little 
milk  there  is  in  the  pail,  the  sample  will  represent  ^6 
part  of  the  milk.     For  composite  sampling  of  the  milk 
of  single  cows,  this  proportion  will  prove  about  right; 
if  more  milk  is  wanted  for  a  sub-sample,  dip  twice,  or 
pour  the  milk  to  be  sampled  into  a  can  of  smaller  diam- 
eter.    If  the  mixed  milk  from  a  number  of  cows  is  to 
be  sampled,  a  wider  sampling  can  may  be  used.     By  ad- 
justing the  diameters  of  the  tube  and  the  can,  any  de- 
sired proportion  of  milk  can  be  obtained  in  the  sample. 

For  factory  sampling,  with  a  weighing  can  26  inches 
in  diameter,  a  tube  three-quarters  of  an  inch  in  diameter 
will  be  found  of  proper  dimensions. 

In  using  these  tubes,  the  milk  or  cream  must  in  all 
cases  be  in  cylindrical  cans  when  the  sample  is  drawn. 

The  sampling  tube  will  furnish  a  correct  sample  of 
the  milk  in  the  can,  even  if  this  has  been  left  standing 
for  some  time;  it  is  better,  however,  to  take  out  the 
sample  soon  after  the  milk  has  been  poured  into  the  can, 
as  the  possible  error  of  cream  adhering  to  the  sides  of 
the  sampling  tube  is  then  avoided. 

185.  The  accuracy  of  the  sampling  of  milk  by  means 
of  the  Scovell  tube  was  proved  beyond  dispute  in  the 
breed  tests  conducted  at  the  World's  Columbian  Expo- 
sition in  1893,  in  which  tests  this  method  was  adopted 

1  The  contents  of  a  cylinder  are  represented  by  the  formula  Tfr^h,  r 
being  the  radius  of  the  cylinder,  and  h  its  height.  The  relation  brtwrei) 
two  cylinders  of  the  same  height,  the  radii  of  which  are  7\*  and  r.  Is 
therefore  as  7TR2h  to  7Tr2h,  or  as  R2  to  r2. 


Composite  Samples  of  Milk. 


163 


for  sampling  the  milk  produced  by  the  single  cows  and 
the  different  herds.1  The  data  obtained  in  these  breed 
tests  also  furnish  abundant  proof  of  the  accuracy  of  the 
Babcock  test. 

186.  d.  The  McKay  sampler  (fig.  53),  constructed  by 
Professor  G-.  L.  McKay,  of  Iowa  experiment  station, 

consists   of  two   nickel-plated  brass 

tubes  that  telescope  one  within  the 

other;    both  have   a  milled  slot  so 

made   that  when 

the  handles  stand 

together   the  slot 

is  open:  by  turn- 
ing   the    handles 

at    right     angles 

the  slot  is  closed. 

The    sampler    is 

made    in    two 

lengths,    21    and 

18     inches,     and 

has    been    found 

very     convenient 

for   sampling 
either  milk  or  cream. 

i86a.  e.  Michels'  cream-sampling 
tube.  Pig.  54  shows  a  section  through 
a  modified  Scovell  sampler  in  a  tin 
heater  recently  invented  by  Prof. 
John  Michels  of  North  Carolina  agricultural  college. 

1  Kentucky  experiment  station,  8th  report,  pp.  xxx-xxxi.  Another 
form  of  a  milk  sampling  tube  in  use  at  the  Iowa  experiment  station  was 
described  and  illustrated  by  Mr.  Eckles  in  Breeder's  Gazette,  May  19, 
1897. 


FIG.  53.    The  McKay 
sampler. 


FIG.  54.    Michels' 

cream  sampling 

tube. 


164  Testing  Milk  and  Its  Products. 

This  sampler  renders  possible  an  accurate  and  rapid 
sampling  of  any  cream,  regardless  of  its  richness  and 
acidity,  without  stirring  the  cream.  The  following  is  a 
description  of  this  sampler,  with  directions  for  using  it : 

A  is  a  steam  and  hot  water  reservoir  with  an  inlet  at  B.  The 
steam  and  hot  water  discharge  through  a  circle  of  small  openings 
at  D.  The  condensed  steam  finds  exit  at  C.  E  is  a  Scovell  sam- 
pler provided  with  a  handle  G,  and  a  circular  piece  of  heavy  tin 
K,  which  holds  the  sampler  in  position  and  prevents  the  escape 
of  steam.  F  is  a  strong  wire  attached  to  the  cap  which  opens 
and  closes  the  sampler.  The  wire  ends  at  the  top  in  a  right 
angle  turn,  H,  which  rests  across  the  top  of  the  sampler  when 
the  lattei^  is  open.  The  construction  of  the  heater  prevents  the 
entrance  of  water  into  the  sampler  and  necessitates  the  use  of 
but  a  very  small  amount  of  steam,  which  is  admitted  through 
the  steam  hose,  I.  The  latter  connects  with  J  leading  to  the 
boiler. 

When  ready  to  sample,  remove  the  sampler  from  the  heater, 
plunge  at  once  to  thei  bottom  of  the  can  of  cream  to  be  sampled, 
and  remove  quickly.  While  holding  the  composite  sample  jar  in 
the  left  hand,  discharge  the  contents  of  the  sampler  into  it  by 
pressing  down  on  H  with  the  thumb  of  the  hand  holding  the 
sampler.  Owing  to  the  heated  condition  of  the  sampler,  the 
cream  discharges  instantly  and,  what  is  equally  important,  all  of 
it  discharges. 

The  sampler  is  pronounced  accurate,  quick,  conven- 
ient and  simple,  and  makes  the  sampling  of  heavy,  rich 
cream,  or  thick,  sour  cream,  no  more  difficult  than  that 
of  milk. 

187.  f.  Composite  sampling  with  a  "one-third  sample 
pipette."  Milk  is  sometimes  sampled  directly  from  the  weighing 
can  into  the  Babcock  test  bottle  by  means  of  a  pipette  holding 
5.87  cc.,  which  is  one-third  the  size  of  the  regular  pipetto.  This 
quantity  is  measured  into  the  test  bottle  from  three  success! vi- 
le ts  of  milk  from  thei  same  patron  and  the  test  then  made  in  the 
ordinary  manner.  In  this  way  one  test  shows  the  average  com- 
position of  the  milk  delivered  during  three  successive  days  or, 
deliveries.  When  this  method  is  adopted,  as  many  test  bottles 


Composite  Samples  of  Milk. 


165 


are  provided  as  there  are  patrons;  there  is  no  need  of  using  any 
preservatives  for  milk  in  this  case.  Fig.  55  shows  a  convenient 
rack  for  holding  the  test  bottles  used  in  composite  sampling  with 
a  * '  one-third  sample  pipette. ' ' 

Accurate  results  can  be  obtained  by  this  method  of  sampling, 
if  care  is  taken  in  measuring  out  the  milk,  and  if  it  is  not  frozen 
or  contains  lumps  of  cream. 
It  is  doubtful  if  the  method 
has  any  advantage  over  the 
usual  method  of  composite 
sampling.  If  milk  is  deliv- 
ered daily  and  each  lot  is 
sampled  with  the  one-third 
pipette,  twice  or  three  times 
the  number  of  tests  are  re- 
quired as  when  composite 
samples  are  taken  in  jars 
and  tested  once  every  week 
or  ten  days.  This  method 
furthermore  takes  a  little 
more  time  in  the  daily  sam- 
pling than  the  other,  as  the 
quantity  of  milk  must  be 
measured  out  accurately  each 
time.  If  a  test  bottle  is  accidently  broken  or  some  milk  spilled, 
the  opportunity  of  ascertaining  the  fat  content  of  the  milk  de- 
livered during  the  three  days  is  lost;  if  a  similar  accident  should 
occur  in  testing  composite  samples  collected  in  jars,  another  test 
can  readily  be  made. 

188.  Accuracy  of  the  described  methods  of  sam- 
pling. An  experiment  made  at  the  Wisconsin  Dairy 
School  may  here  be  cited,  showing  that  concordant  re- 
sults willl  be  obtained  by  the  use  of  the  drip  sampling 
method  and  the  Scovell  tube.  Two  composite  samples 
were  taken  from  fifty  different  lots  of  milk,  amounting 
to  about  6,000  Ibs.  in  the  aggregate.  One  sample  was 
taken  of  the  drip  from  a  hole  in  the  conductor  spout 


FIG.  55.    Test-bottle  rack  for  use  in 
crenmeries  and  cheese  factories. 


166  Testing  Milk  and  Its  Products. 

through  which  the  milk  passed  from  the  weighing  can; 
the  other  was  taken  from  the  weighing  can  by  means 
of  a  Scovell  sampling  tube.  The  following  percentages 
of  fat  were  found  in  each  of  these  samples  r1 


Babcock  test 

Gravimetric 
analysis 

Drip  composite  sample   

4  0  per  cent 

'  4  04  percent 

Scovell  tube  composite  sample.. 

4.0  per  cent. 

4.  06  per  cent. 

PRESERVATIVES  FOR  COMPOSITE   SAMPLES. 

189.  When  milk  is  kept  for  any  length  of  time  under 
ordinary  conditions,  it  will  soon  turn  sour  and  become 
loppered,    and    further   decomposition   shortly   sets   in, 
which  renders  the  sampling  of  the  milk  both  difficult 
and  unsatisfactory  (19).   The  period  during  which  milk 
will  remain  in  an  apparently  sweet  or  fresh  condition 
varies  with  the  temperature  at  which  it  is  kept,  and 
with  the  cleanliness  of  the  milk.     It  will  not  generally 
remain  sweet  longer  than  two  days  at  the  outside,  at 
ordinary  summer  or  room  temperature. 

In  order  to  preserve  composite  samples  of  milk  in  a 
proper  condition  for  testing,  some  chemical  which  will 
check  or  prevent  the  fermentation  of  the  milk  must  be 
added  to  it.  A  number  of  substances  have  been  pro- 
posed for  this  purpose. 

190.  Bi-chromate    of    potash.      This  preservative   is 
preferred  by   many  because  it  is  relatively  harmless, 
cheap  and  efficient.     The  bi-chromate  method  for  pre- 
serving samples   of  milk  was  proposed  by  Mr.   J.   A. 
Alen,  city  chemist   of  Gothenburg,   Sweden,  in   1892,2 

1  See  also  199  et  seq. 

2  Biedermann's  Oentralblatt,  1892,  p.  549. 


Composite  Samples  of  ]\iilk.  167 

and  has  been  generally  adopted  in  dairy  regions  in  this 
country  and  abrcad.  While  not  perfectly  harmless,  the 
bi-chromate  is  not  a  violent  poison  like  other  chemicals 
proposed  for  this  purpose,  and  no  accidents  are  liable 
to  result  from  its  use. 

191.  The  quantity  cf  bi-chromate  necessary  for  pre- 
serving half  a  pint  to  a  pint  of  milk  for  a  period  of 
one   or  two  weeks   is  abcut   one-half   gram    (nearly   8 
grains). 

According  to  Winton  and  Ogden,1  a  .22-inch  pistol 
cartridge  shell  %  inch  long,  cr  a  .32-inch  caliber  shell 
1/4  inch  long,  when  loosely  filled,  will  hold  enough  pow- 
dered bi-chromate  to  preserve  y2  pint,  and  a  .32-inch 
caliber  shell  %  inch  long  will  hold  enough  to  preserve 
one  pint.  These  shells  may  be  conveniently  handled 
by  soldering  to  them  a  piece  of  stiff  wire  which  serves 
as  a  handle.  The  amount  of  bi-chromate  placed  in 
each  composite  sample  jar  would  fill  about  half  the 
space  representing  one  per  cent,  in  the  neck  of  a  Bab- 
cock  milk  test  bottle. 

192.  The  first  portions   of   milk   added  to   the   com- 
posite sample  jars  containing  the  specified  amount  of 
bi-chromate  will  be   colored   almost  red,   but   as  more 
milk  is  added  day  by  day,  its  color  will  become  lighter 
yellow.     The  complete  sample  should  have  a  light  straw 
color;  such  samples  are  most   easily  mixed   with   acid 
when  tested.     If  more  bi-chromate  is  used,  the  solution 
of  the  casein  in  the  acid  is  rendered  difficult  and  re- 
quires persistent  shaking.     Bi-chromnte  can  be  bought 

1  Connecticut  experiment  station,  report  for  1884,  p.  W2. 


168  Testing  Milk  and  Its  Products. 

at  drug  stores  or  from  dairy  supply  dealers  at  about  30 
cents  a  pound.  Powdered  bi-chromate  of  potash  should 
be  ordered,  and  not  crystals,  as  the  latter  dissolve  only 
slowly  in  the  milk.  Bi-chromate  tablets  contain  the 
correct  quantity  of  preservative  for  a  quart  sample,  and 
will  be  found  convenient. 

193.  Other  preservatives  for  composite  samples. 
Among  other  substances  recommended  for  use  in  butter 
or  cheese  factories  as  milk  preservatives  for  composite 
samples  are  formalin,  boracic-acid  compounds,  chloro- 
form, carbon  bi-sulfid,1  copper  ammonium  sulfate,  so- 
dium fluorid,  ammonia  glycerin  (sp.  gr.,  1.031),  and 
mixtures  containing  mercuric  chlorid  (corrosive  sub- 
limate) with  anilin  color  (rosanilin).2  The  coloring 
matter  in  the  latter  compounds  is  added  to  give  a  rose 
color  to  the  sample  preserved,  thus  showing  that  the 
milk  is  not  fit  for  consumption;  the  bi-chromate  giving 
naturally  a  yellow  color  to  the  milk,  renders  unneces- 
sary the  addition  of  any  special  coloring  matter. 

The  compounds  containing  corrosive  sublimate  are 
violent  poise ns  and  must  always  be  handled  with  the 
greatest  care,  lest  they  get  into  the  hands  of  children  or 
persons  not  familiar  with  their  poisonous  properties; 
they  will  preserve  the  milk  longer  than  bi-chromate 
when  applied  in  sufficient  quantities.  During  late  years 
corrosive  sublimate  tablets  have  come  into  general  use 
in  factories. 

1  Delaware  experiment  station,  eight  li  report,  IS<M>,  which  also  sec  for 
trials  with  a  lar^e  number  of  dilTerent  preservat  i\  ••>. 

2  Iowa  experiment  station,  bulletins  (.»,  11,  iW. 


Composite  Samples  of  Milk.  169 

194.  Care   of   composite    samples.      The    composite 
sample  jars  should  be  kept  covered  to  prevent  loss  by 
evaporation,  and  in  a  cool,  dark  place,  or  at  least  out 
of  direct  sunlight  when  bi-chromate  of  potash  is  used 
as  a  preservative;  the  chromic  acid  formed  by  the  re- 
ducing influence   of   light  on   chromate   solutions   pro- 
duces a  leathery  cream  which  is  difficult  to  dissolve  in 
sulfuric  acid. 

A  coating  of  white  shellac  has  been  suggested  to  pro- 
tect the  labels  of  the  composite  sample  jars.  The  shel- 
lac is  applied  after  the  names  of  the  patrons  have  been 
written  on  the  labels,  and  when  these  have  been  put  on 
the  jars.  Gummed  labels,  1x2%  inches,  answer  this 
purpose  well. 

Numbers  are  sometimes  ground  on  the  sample  jar  or 
stamped  on  brass  tags  attached  to  the  jars  by  a  wire. 

In  keeping  the  milk  from  day  to  day,  care  should  be 
taken  that  the  cream  forming  on  the  milk  does  not  stick 
to  the  sides  of  the  jars  in  patches  above  the  level  of  the 
milk.  Unless  the  daily  handling  of  the  jars  and  the 
addition  of  fresh  portions  of  milk  be  done  with  suffi- 
cient care,  the  cream  will  become  lumpy  and  will  dry 
on  the  sides  of  the  jars.  In  some  cases  it  is  nearly  im- 
possible to  evenly  distribute  this  dried  cream  through 
the  entire  sample  at  testing  time  so  as  to  make  the  com- 
posite sample  a  true  representative  of  the  different  lots 
of  milk  from  which  it  has  been  taken. 

195.  Every  time  a  new  portion  of  milk  is  added  to 
the  jar  this  should  be  given  a  gentle  horizontal  rotary 


170  Testing  Milk  and  Its  Products. 

motion,  thereby  mixing  the  cream  already  formed  in 
the  jar  with  the  milk  and  loosening  the  cream  stick- 
ing to  its  side.  This  manipulation  also  prevents  the 
surface  of  the  milk  from  becoming  covered  with  a  layer 
of  partially  dried  leathery  cream. 

Composite  samples  having  patches  of  dried  cream  on 
the  inside  of  the  jar  are  the  result  of  carelessness  or 
ignorance  on  the  part  of  the  operator.  If  proper  at- 
tention is  given  to  the  daily  handling  of  the  composite 
samples,  the  cream  formed  in  the  jars  can  again  be 
evenly  mixed  with  the  milk  without  difficulty. 

196.  Fallacy  of  averaging  percentages.  A  composite 
sample  of  milk  should  represent  the  average  quality 
of  the  various  lots  of  milk  of  which  it  is  made  up.  This 
will  be  true  if  a  definite  aliquot  portion*  or  fraction  of 
the  different  lots  of  milk  is  taken.  If  the  weights  of, 
say  ten  different  lots  of  milk,  are  added  together  and 
the  sum  divided  by  ten,  the  quotient  will  represent  the 
average  weight  per  lot  of  milk,  but  an  average  of  the 
tests  of  the  different  lots  obtained  in  this  way  may  not 
be  the  correct  average  test  of  the  entire  quantity  of 
milk.  The  accuracy  of  such  an  average  figure  will  de- 
pend on  the  uniformity  in  the  composition  and  weights 
of  the  ten  lots  of  milk.  When  there  is  no  uniformity, 
the  weights  of  the  different  lots  of  milk  as  well  as  their 
tests  must  be  considered.  The  following  example  will 
illustrate  the  difference  between  the  arithmetical  aver- 
age of  a  number  of  single  tests  and  the  true  average  test 
of  the  various  lots. 


Composite  Samples  of  Milk.  171 

Methods  of  calculating  average  percentages. 


I.  Milk  varying  in  weights  and  tests. 

II.  Milk  of  uniform  weights  and  tests. 

LOT. 

Weight 
of  milk. 

Test 
of  milk. 

Weight 
of  fat. 

LOT. 

Weight 
of  milk. 

Test 
of  milk. 

Weight 
of  fat. 

I 

Ibs. 

120 
570 
360 
55 

82 

per  ct. 

3.5 
5.0 
5.2 
3.0 
4.0 

Ibs. 

4.2 
28.5 
18.7 
1.6 
3.2 

I 

Ibs. 

250 
225 
240 
238 
234 

per  ct. 

4.2 
4.0 
4.3 
4.1 
4.4 

Ibs. 

10.5 
9.0 
10.3 
9.7 
10.3 

II 

II  .. 
Ill  .. 

III  .. 

IV 

IV 

V  

V  

Total  

Total  

1187 
237 

56.2 
11.24 

1187 
237 

49.8 
10.0 

Average.. 

True  aver- 
age test... 

4.14 
4.73* 

Average  

True  average 
test  

4.20 
4  22+ 

i 

*56. 2X100 
1187 


=4.73. 


+49.8X100 
1187 


197.  The  figures  given  in  the  table  show  that  when 
the  different  lots  of  milk  vary  in  test  and  weight,  as  in 
the  first  case,  the  correct  average  test  of  the  1187  Ibs. 
of  milk  is  not  found  by  dividing  the  sum  of  these  tests 
by  five,  which  would  give  4.14  per  cent. ;  but  the  per- 
centage which  56.2  (the  total  amount  of  fat  in  the 
mixed  milk)  is  of  1187  (the  total  amount  of  milk),  is 
4.73,  and  this  is  the  correct  average  test  of  the  mixed 
milk  made  up  of  the  five  different  lots. 

In  the  second  case,  the  variations  in  both  the  weights 
of  the  different  lots  of  milk  and  their  tests,  are  com- 
paratively small,  and  both  methods  of  calculation  give 
therefore  practically  the  same  average  test;  but  also  in 
this  case,  the  correct  average  test  is  found  by  dividing 
the  total  amount  of  fat  by  the  total  quantity  of  milk, 
making  4.22  per  cent.,  instead  of  4.20  per  cent.,  wnich  is 


172  Testing  Milk  and  Its  Products. 

the  arithmetical  mean  of  the  five  tests.  The  quantities 
of  milk  in  the  various  lots  do  not  enter  into  the  calcula- 
tion of  the  latter.1 

198.  The  second  example  represents  more  nearly 
than  the  first  one  the  actual  conditions  met  with  at 
creameries  and  cheese  factories.  As  a  rule,  the  mixed 
milk  from  a  herd  of  cows  does  not  vary  more  in  total 
weight  or  tests,  within  a  short  period  of  time  like  one 
to  two  weeks,  than  the  figures  given  in  this  example. 
On  account  of  this  fact,  samples  taken,  for  instance, 
with  a  small  dipper  may  give  perfectly  satisfactory  re- 
sults to  all  parties  concerned.  If  the  different  lots  of 
milk  varied  in  weight  and  test  from  day  to  day,  as 
shown  in  the  first  case,  it  would  be  necessary  to  use  a 
"milk  thief"  or  one  of  the  sampling  tubes  for  taking 
the  composite  samples;  the  size  of  each  of  the  samples 
taken  would  then  represent  an  exact  aliquot  portion  of 
the  various  lots  of  milk  (182). 

199.  A  patron's  dilemma.  The  following  incident  will  fur- 
ther explain  the  difficulties  met  with  in  calculating  the  average 
tests  of  different  lots  of  milk. 

Thel  weekly  composite  sample  of  the  milk  supplied  by  a  cream- 
ery patron  from  his  herd  of  21  cows  tested  4.0  per  cent.  fat. 
One  day  the  farmer  brought  to  the  creamery  a  sample  of  the 
morning's  milk  from  each  of  his  cows,  and  had  thorn  tested; 
after  adding  the  tests  together  and  dividing  the  sum  by  21,  he 
obtained  an  average  figure  of  5.1  per  cent,  of  fat.  From  this 
he  concluded  that  the  average  test  of  the  milk  from  his  cows 
ought  to  be  5.1,  instead  of  4.0,  and  naturally  asked  for  an  ei 
planation. 

1  In  the  experiment  Driven  on  p.  146,  the  arithmetical  nn-jin  of  tin- 
tests  Is  5.15  per  cent.,  while  the  true  average  fat  content  of  milk  is 
4.85  per  cent. 


Composite  Sa 


The  first  thing  done  was  to  show  him  that  while  5.1  was  the 
correct  average  of  the  figures  representing  the  tests  of  his 
twenty-one  cows,  it  was  not  a  correct  average  test  of  the  mixed 
milk  from  all  his  cows,  as  he  had  not  considered,  in  calculating 
this  average,  the  quantities  of  milk  yielded  by  each  cow;  the 
following  illustration  was  used: 

Cow  No.  1,  yield  25  Ibs.  of  milk,  test  3.6  per  cent.=0.9  Ib.of  butter  fat. 
Cow  No.  2,  yield   6  Ibs.  of  milk,  test  5.0  per  cent.  =0.3  Ib.  of  butter  fat. 

Total  .......  31  Ibs.  2)8.6  1.2  Ibs. 

4.3  per  cent. 

The  two  cows  gave  31  Ibs.  of  milk  containing  1.2  Ibs.  of  fat; 
the  test  of  the  mixed  milk  would  therefore  not  be  4.3  per  cent. 
/3.65.0\  but  1.2X100  =3tg7  per  cent  If  the  fat  in  th 


t         per 

milk  was  calculated  by  the  average  figure  4.3  per  cent.,  1.33  Ibs. 
of  fat  would  be  obtained,  i.  e.,  0.13  Ib.  more  than  the  cows  pro- 
duced. 

In  order  to  further  demonstrate  the  actual  composition  of  the 
mixed  milk  of  the  twenty-one  cows,  the  milk  of  each  cow  was 
weighed  and  tested  at  each  of  the  two  niilkings  of  one  day.  The 
weights  and  tests  showed  that  the  cows  produced  the  following 
total  number  of  pounds  of  milk  and  of  fat: 

Morning  milking,  113.3  Ibs.  of  milk,  containing  5.17  Ibs.  of  fat. 
Night  milking,       130  9  Ibs.  of  milk,  containing  4.98  Ibs.  of  fat. 

The  morning  milk  therefore   contained   5-  7X*°°:=:4.56  per   cent. 

1  13  .  3 


of  fat,  and  the  night  milk,  4-^^°°=3.80  per  cent,  of  fat. 

The  sum  of  the  morning  and  night  milkings  gave:  milk,  244.2 
Ibs.,  fat  10.15  Ibs.  The  mixed  morning  and  night  milk,  there- 
fore, contained  10-^4X*00  =  4.1  per  cent,  of  fat.  This  is  the  true 
average  test  of  the  morning  and  night  milkings  of  these  twenty- 
one  cows,  as  found  by  weighing  and  testing  separately  the  milk 
of  each  cow  at  both  milkings. 

The  total  milk  was  strained  into  a  large  can  at  the  farm,  both 
in  the  morning  and  in  the  evening.  A  sample  of  the  mixed  milk 
was  in  each  case  taken  with  a  long-handled  dipper  as  soon  as 
the  milkings  were  finished.  When  the  cans  of  milk  were  deliv- 


174 


Testing  Milk  and  Its  Products. 


ered  at  the  creamery,  a  sample  of  each  was  taketn  with  a  Scovell 
sampling  tube.  The  tests  of  these  four  samples  are  given  below, 
together  with  the  results  of  the  individual  tests: 


Morning  Milk. 

Night  Milk. 

Sample  taken  at  the  farm,  with  dipper.  . 
Sample  taken  at  creamery  with  Scovell 
tube  

4.4  per  ct. 
4.5        " 

3.8  per  ct. 
3.7        " 

Calculated   from   weights   and   tests   of 
milk  from  each  cow 

45        " 

3.8        " 

The  figures  given  show  that  practically  uniform  tests  were  ob- 
tained by  the  different  methods  of  sampling. 


Questions. 

1.  What  is  a  composite  sample  of  milk? 

2.  Describe  the  proper  care  of  composite  samples. 

3.  Give  an  example  showing  that   composite  samples  of  milk 
may  be  inaccurate  when   taken  with  a  small   dipper. 

4.  Describe  the  construction  of  the  following  methods  of  sam- 
pling milk  or  cream,  by    (a)   drip  sample,    (b)    the  Scovell,    (c) 
the  McKay,  and   (d)   the  Michels'  sampling  tubes. 

5.  What  is   the   purpose  of  adding  preservatives   to   milk   or 
cream    samples?     Mefntion   the   more    common    preservatives   used 
and  quantities  to  be  added. 


CHAPTER  XI. 
CREAM  TESTING  AT  CREAMERIES. 

.  200.  The  cream  delivered  at  gathered-cream  factories 
is  now  in  many  localities  tested  by  the  Babcock  test,  and 
this  has  been  adopted  as  a  basis  of  paying  for  the  cream 
in  the  same  manner  as  milk  is  paid  for  at  separator 
creameries.  It  has  been  found  to  be  more  satisfactory 
to  both  cream  buyer  and  seller  than  either  the  oil-test 
churn  or  the  space  (or  gauge)  systems  which  have  been 
used  for  this  purpose  in  the  past. 

The  details  of  the  application  of  the  Babcock  test  to 
the  practical  work  at  cream-gathering  creameries  have 
been  carefully  investigated  by  Winton  and  Ogden  in 
Connecticut,1  Bartlett  in  Maine,2  and  Lindsey  in  Massa- 
chusetts,3 and  we  also  owe  to  the  labors  of  these  chem- 
ists much  information  concerning  the  present  workings 
of  other  systems  of  paying  for  the  cream  delivered  at 
creameries. 

201.  The  space  system.  Numerous  tests  have  shown 
that  one  space  or  gauge  of  cream  does  not  contain  a 
definite,  uniform  amount  of  fat.  In  over  100  compari- 
sons made  by  Winton  it  was  found  that  one  space  of 
cream4  contained  from  .072  to  .170  Ib.  of  butter  fat,  or 

1  Conn,  experiment  station  (New  Haven),  bull.  108  and  119;  report 
1894,  pp.  214-244. 

2  Maine  experiment  station,  bull.  3  and  4  (S.  S.) 

3  Hatch  experiment  station,  report  1894,  pp.  92-103;  1895,  pp.  67-70. 

4 The  space  is  the  volume  of  a  cylinder,  8%  inches  in  diameter  and 
AS  of  an  inch  high.  The  number  of  spaces  in  each  can  of  milk  is  read  off 
before  skimming  by  means  of  a  scale  marked  on  a  strip  of  glass  in  the 
side  of  the  can  (Conn.  exp.  sta.,  bull.  119). 


176 


Testing  Milk  and  Its  Products. 


on  the  average  .13  lb.,  and  the  number  of  spaces  re- 
quired to  make  one  pound  of  butter  varied  from  5.01  to 
11.72.  It  is  also  claimed  that  in  the  winter  season  when 
the  cream  is  gathered  at  long  intervals,  like  once  a  week, 
it  is  necessary  for  the  buyer  to  accept  the  seller's  state- 
ment of  the  record  of  the  number  of  cream  spaces  which 
he  furnishes,  since  the  cream  cannot  be  left  in  the 
creaming  can  for  so  long  a  time.  These  objections  to 
the  space  system  apply  only  to  the  method  of  paying 
for  the  cream,  and  not  to  the  manner  in  which  the 
cream  is  obtained. 

202.  The  oil-test  churn.     As  stated  in  the  introduc- 
tion, the  oil-test  churn  (fig.  56)  has  been  used  quite  ex- 
tensively among  gath- 
ered-cream      factories ; 
this  system  is  based  on 
the   number   of  inches 
of    cream    which    the 
various  patrons  deliver 
to      the      factory;      a 
creamery    inch    is    the 
quantity  of  cream 
which   will   fill   a   can 
twelve  inches  wide,  one 
inch  high ;  it  contains 
113  cubic  inches.1  This 
quantity  was  supposed  to  make  one  pound  of  butter. 
In  using  this  method  the  driver  pours  the  patron's 
cream  into  his  12-inch  gathering  pail,  measures  it  with 

1  A  layer  of  two  inches  in  an  8-inch  pail  contains  101  >.">:;  i  rul>ir  inches. 
two  inches  In  a8%-inch  pail  110.18  cubic  inches  and  2  inches  in  a  8%-im'li 
pail  113.49  cubic  inches. 


FIG.  56.    The  oil-test  churn. 


Cream  Testing  at  Creameries. 


Ill 


his  rule  and  records  the  depth  of  the  cream  in  the  can, 
in  inches  anol  tenths  of  an  inch.  The  cream  is  then 
stirred  thoroughly  with  a  ladle  or  a  stout  dipper,  and 
sampled  by  filling  a  test  tube  to  the  graduation  mark 
by  means  of  a  small  conical  dipper  provided  with  a 
lip.  A  driver's  case  contains  either  two  or  three 
"cards,"  holding  fifteen  test  tubes  each  (see  fig.  57). 
The  tubes  as  filled  are 
placed  in  the  case  and 
the  corresponding  num- 
ber in  each  instance  re- 
corded in  front  of  the 
patron's  name,  together 
with  the  number  of 
inches  of  cream  fur- 
nished by  him. 

On  the  arrival  at  the 

. .  FIG.  57.    Cream-gatherer's 

nunnery  the  tin   cards  sample  case, 

holding  the  tubes  are  p]aced  in  a  vessel  filled  with 
water  of  the  temperature  wanted  for  churning  (say,  60° 
in  summer  and  65°  to  70°  in  winter).  When  ready  for 
churning  they  are  placed  in  the  oil-test  churn,  the  cover 
of  the  churn  put  on,  and  the  samples  of  cream  churned 
to  butter.  On  the  completion  of  the  churning,  the  cards 
are  transferred  to  water  of  175-190°  Fahr.,  where  they 
are  left  for  at  least  ten  minutes  to  melt  the  butter  and 
"cook  the  butter  milk  into  a  curd."  The  oil  will  now 
be  seen  mixing  through  the  mass.  The  test  tubes  are 
then  warmed  to  churning  temperature  and  churned 
again,  by  which  process  the  curd  is  broken  into  fine 

12 


178  Testing  Milk  and  Its  Products. 

particles,  which,  when  the  butter  is  re-melted,  will  set- 
tle to  the  bottom.  The  butter  is  melted  after  the  sec- 
ond churning  by  placing  the  tubes  in  water  at  150-175° 
F.,  allowing  them  to  remain  therein  for  at  least  twenty 
minutes.  'Some  samples  must  be  churned  three  or  four 
times  before  a  gcod  separation  of  oil  is  obtained.  A 
clear  separation  of  oil  is  often  facilitated  by  adding  a 
little  sulfuric  acid  to  the  tubes. 

The  length  of  the  column  of  liquid  butter  fat  is  de- 
termined by  means  of  a  special  rule  for  measuring  the 
butter  oil ;  this  rule  shows  the  number  of  pounds  and 
tenths  of  a  pound  of  butter  which  an  inch  of  cream  will 
make;  the  first  tenth  of  a  pound  on  the  rule  is  divided 
into  five  equal  parts,  so  that  measurements  may  be  made 
to  two-hundredths  of  a  pound.  The  melted  fat  is  meas- 
ured with  the  rule,  by  raising  the  tin  card  holding  the 
bottles,  to  about  the  height  of  the  eye ;  the  reading  is 
recorded  on  the  driver's  tablet  under  Test  per  incli,  op- 
posite the  number  of  the  particular  patron.  The  test 
per  inch  multiplied  by  the  inches  and  tenths  of  an  inch 
of  cream  supplied  will  give  the  butter  yield  in  pounds, 
with  which  the  patron  will  be  credited  on  the  books  of 
the  creamery. 

203.  The  objection  to  this  system  of  ascertaining  the 
quality  cf  cream  delivered  by  different  patrons  lies  in 
the  fact  that  it  determines  the  churnable  fat,  and  n<>1 
the  total  fat  of  the  cream;  the  amount  of  the  former 
obtained  depends  on  many  conditions  beyond  the  con- 
trol of  the  patron,  viz.,  the  consistency,  acidity  and  tem- 
perature of  the  cream,  the  size  of  the  churn  or  churn 


Cream  Testing  at  Creameries.  179 

ing  vessel,  etc.1  The  same  reasons  which  caused  the 
churn  to  be  replaced  by  methods  of  determining  the 
total  fat  of  the  milk,  in  the  testing  of  cows  among  dairy- 
men and  breeders,  have  gradually  brought  about  the 
abandonment  of  the  oil  test  in  creameries  and  the  adop- 
tion of  the  Babcock  test  in  its  place.  It  may  be  said, 
en  the  other  hand,  in  favor  of  the  use  of  the  oil  test  in 
creameries  that  it  is  a  considerably  cheaper  method 
than  any  fat  test,  and  -calls  for  an  expenditure  of  less 
labor  and  time  on  the  part  of  the  operators  than  do  the 
latter  methods. 

204.  The  Babcock  test  for  cream.  Both  the  space 
system  and  the  oil-test  churn  used  for  estimating  the 
quality  of  cream  at  creameries  have  now  largely  been 
replaced  by  the  Babcock  test  in  the  more  progressive 
creameries  in  this  country,  and  composite  samples  of 
cream  are  collected  and  tested  in  a  similar  manner  as 
is  done  with  milk  at  separator  creameries  and  cheese 
factories. 

A  very  satisfactory  method  of  arrangements  for 
working  the  Babcock  test,  in  use  in  many  eastern  cream- 
eries, is  described  by  Winton  and  Ogden  in  the  Con- 
necticut report  previously  referred  to.  The  cream 
gatherer  who  collects  the  cream  in  large  cream  cans  is 
supplied  with  a  spring  balance  (1,  see  fig.  58),  pail  for 
sampling  and  weighing  the  cream  (2),  sampling  tube 
(3),  and  collecting  bottles  (5).  At  each  patron's  farm 
he  takes  from  his  wagon  the  sampling  pail  and  tube, 

1  It  follows  from  this  that  there  can  be  no  definite  relation  between 
the  results  obtained  by  the  Rabcock  test  and  the  oil-test  readings;  or- 
dinarily a  reading  of  100  In  the  oil-test  Is  equlvelant  to  about  23  per 
cent,  of  butter  fat  in  the  cream. 


180 


Testing  Milk  and  Its  Products. 


the  scales,  and  one  small  collecting  bottle.  He  should 
find  in  the  dairy  of  the  patron  the  cans  of  perfectly 
sweet  cream,  kept  at  a  temperature  of  40°  to  50°  F., 

and  protected  from  dirt 
and  bad  odors.  Either  sour 
or  frozen  cream  must  be 
rejected.  The  patron's 
number  should  be  painted 
in  some  conspicuous  place 
nfcar  the  cream  cans  in  his 
dairy  house.  The  gatherer 
hangs  the  scale  on  a  hook 
near  the  cream  to  be  col- 
lected; the  scale  should  be 
made  so  that  the  hand  of 

FIG.  58.  Outfit  for  cream  testing  f>,0  /JiQl  ™71*n  etanrl  at  -/o^n 
by  the  Babcock  test  at  gathered-  tne  Cial  Wl11  stana  at  zei 

when  the  empty  pail  is 

hung  on  it.  The  cream  is  then  poured  at  least  twice 
from  one  can  to  another  in  order  to  mix  it  thoroughly.1 

205.  When  properly  mixed,  the  cream  is  poured  into 
the  weighing  pail  and  is  weighed  and  sampled.  The 
authors  give  the  following  description  of  the  cream 
sampling  tube  used,  and  directions  for  sampling  and 
weighing  the  cream. 

"Sampling  Tube. — This  tube  is  of  stout  brass,  about  .^  :>f  an 
inch  thin-k.  and  a  few  inches  longer  than  the  weighing  pail  which 

1  The  necessity  of  care  In  mixing:  the  cream  is  shown  l>y  t  In-  follow- 
ing illustration  given  by  the  authors  referred  to. 

Per  cent  of  fat  in  cream  which  stood  for  ."/  ?nmr*. 

Sample  dr;i\vn 
Surface.  Bottom.  with  sampling  tube. 

Not  mixed 28.00  5.00  19.25 

Poured  once 28.75  22.00  22.50 

Poured  twice...  ».» 


Testing  Cream  at  Creameries.  181 

is  used  with  it.  On  the  upper  end,  a  small  brass  stop-cock  of 
the  same  bore  is  fastened.  It  should  be  nickel  plated  inside  and 
out,  to  keep  the  metal  smooth  and  free  from  corrosion.  These 
tubes  may  be  obtained  from  less  than  T\  to  over  %  inch  bore. 
The  greater  the  diameter  of  the  weighing  pail,  the  wider  should 
be  the  bore  of  the  tube.  For  use  with  pails  8  inches  in  diameter, 
a  -,83  inch  bore  sampling  tube  will  serve  the  purpose,  but  when 
the  pail  has  a  diameter  of  9  or  more  inches,  a  tube  with  a  bore 
of  ^4  inch  or  more  should  be  used.  It  must  be  borne  in  mind 
that  doubling  the  diametetr  of  the  pail,  or  of  the  sampling  tube, 
increases  its  capacity  fourfold. 

"  The  tube  when  not  in  use  should  be  kept  in  an  upright  posi- 
tion to  permit  draining. 

"Sampling  and  Weighing. — Lower  the  sampling  tube,  cock 
end  up,  with  the  cock  open,  to  the  bottom  of  the  weighing  pail 
which  holds  the  mixed  cream.  When  it  is  filled  raise  it  out  of 
the  liquid  and  allow  it  to  drain  for  a  few  seconds.  By  this 
means  the  tube  is  rinsed  with  the  cream  to  be1  sampled  and  any 
traces  of  cream  adhering  to  the  tube  from  previous  use  are  re- 
moved. With  the  cock  still  open,  slowly  lower  the  sampling  tube 
to  the  bottom  of  the  cream  pail.  After  allowing  a  moment  for 
the  cream  to  rise  in  the  tube  to  the  same  height  as  in  the  pail, 
close  the  cock  and  raise  the  sampler  carefully  out  of  the  cream. 
As  long  as  the  cock  is  closed,  the  cream  in  the  tube  will  not 
flow  out,  unless  the  tube  is  strongly  jarred.  Allow  the  cream 
adhering  to  the  outside)  of  the  tube  to  drain  off  for  a  few  sec- 
onds, then  put  the  lower  end  into  the  1  to  1%  oz.  wide-mouth 
glass  collecting  bottle  which  bears  the  patron 's  .  number  on  its 
cork,  and  open  the  cock.  The  cream  will  then  flow  out  of  the 
sampler  into  the  bottle,  which  is  afterwards  securely  corked  and 
put  into  the  cream  gatherer's  case.  Immediately  weigh  the 
cream  in  the  cream  pail  to  the  quarter  or  half  pound,  as  may 
be  judged  expedient,  and  record  the  weight. 

"If  the  patron  has  more  than  one  pailful,  repeat  with  each 
pailful  the  operation  of  sampling  and  weighing,  putting  all  the 
samples  in  one/  and  the  same  bottle.  Weigh  all  cream  collected 
in  one  and  the  same  sampling  pail  and  draw  a  sample  from  each 
separate  portion  weighed." 


182  Testing  Milk  and  Its  Products. 

206.  After    sampling    and    weighing    each    patron's 
cream  it  is  poured  into  the  driver's  large  can,  and  the 
sample  bottles  are  carried  in   a  case  to  the  creamery 
where  the  contents  of  each  bottle  is   poured  into  the 
composite  sample  jar  of   the   particular   patron.     The 
samples  of  cream  in  the  small  bottles,  besides  furnish- 
ing the  means  of  testing  the  richness  of  the  cream,  give 
the  creamery  man  an  opportunity  to  inspect  the  flavor 
of  each  lot  of  cream,  and  the  condition  in  which  it  has 
been  kept  by  the  various  patrons.     Some  preservative, 
usually  corrosive  sublimate  tablets,  is  placed  in  the  com- 
posite sample  jars,  and  these  are  cared  for  and  tested 
in  the  same  manner  as  composite  samples  of  milk  (194). 

207.  The    collecting   bottles   should   be   cleaned   with 
cold,  and  afterwards  with  hot  water,  as  soon  as  they  are 
emptied,   and  before   a  film   of  cream   dries   on  them. 
When  washed  and  dried,  these  bottles  are  placed  in  the 
cases,  ready  for  the  next  collecting  trip.     There  can  be 
no  confusion  of  bottles  since  the  corks  and  not  the  bot- 
tles  are   marked   with   the   numbers   of   the   respective 
patrons. 

208.  When  this  system  of  testing  composite  samples 
is   adopted,   the   patrons   are   paid  for  the  number  of 
pounds  of  butter  fat  contained  in  their  cream,  in  ex- 
actly the  same  way  as  milk  is  paid   for  at  separator 
creameries.     It  makes  no  difference  how  thick  or  how 
thin  the  cream  may  be,  or  how  much  skim  milk  is  left 
in  the  cream  when    brought  to  the    factory.     Eighty 
pounds  of  cream  containing  15  per  cent,  of  fat  is  worth 
no  more  or  less  than  48  pounds  of  cream  testing  25  per 
cent.;  in  either  case  12  pounds  of  pure  butter  fat  is 


Testing  Cream  at  Creameries.  183 

delivered.  This  will  make  the  same  amount  of  butter 
in  either  case,  viz.,  toward  14  Ibs.,  and  both  patrons 
should  therefore  receive  the  same  amount  of  money. 

There  is  a  small  difference  in  the  value  of  the  two 
lots  of  cream  to  the  creamery  owner  or  the  butter  maker, 
in  favor  of  the  richer  cream,  both  because  its  smaller 
bulk  makes  the  transportation  and  handling  expenses 
lighter,  and  because  slightly  less  butter  fat  will  be  lost 

in  the  butter  milk,  a  smaller  quantity  of  this  being  ob- 

% 

tained  from  the  richer  cream.  But  it  is  doubtful  if  the 
differences  thus  occurring  are  of  sufficient  importance 
to  be  noticed  under  ordinary  creamery  conditions;  the 
example  selected  presents  an  extreme  case  of  variation 
in  the  fat  content  of  cream.  A  trial  of  this  system  at 
five  Connecticut  creameries,  supplied  mostly  with  Cooley 
cream,  by  over  175  patrons,  showed  that  the  average 
composition  of  the  cream  from  the  different  patrons 
varied  only  from  16.9  to  19.8  per  cent,  of  fat.  The  cream 
of  some  patrons  on  certain  days  contained  only  9.5  per 
cent,  of  fat,  and  other  patrons  at  times  had  as  high  a 
test  as  30  per  cent.,  but  these  great  differences  largely 
disappeared  when  the  average  quality  of  the  cream 
delivered  during  a  period  of  time,  like  a  month  or  more, 
was  considered. 

209.  Smaller  differences  in  the  composition  of  cream 
will,  however,  always  occur,  even  if  the  same  system  of 
setting  the  milk,  like  the  cold  deep-setting  process,  is 
used  and  the  water  is  kept  at  the  same  temperature  at 
all  times.  This  is  due  to  differences  in  the  composition 
of  the  milk  and  its  creaming  quality;  whether  largely 
from  fresh  cows  or  from  late  milkers;  whether  kept 


184  Testing  Cream  and  Its  Products. 

standing  fcr  a  time  before  being  set,  or  submerged  in 
the  creamer  immediately  after  milking  and  straining, 
diameter  of  creaming  cans,  etc.  Bartlett  states1  that 
the  percentage  of  fat  in  the  cream  from  the  same  cows 
may  be  increased  ten  per  cent,  or  more  by  keeping  the 
water  at  70°  instead  of  at  40°  F.  The  higher  tempera- 
ture will  give  the  richer  cream,  but  the  separation  will 
not  be  so  complete,  since  a  richer  skim  milk  is  obtained 
from  the  milk  set  at  this  temperature.  Separator  cream 
is  not  materially  influenced  by  the  conditions  mentioned, 
as  the  separator  can  be  regulated  to  deliver  cream  of 
nearly  uniform  richness  from  all  kinds  of  sweet  milk. 

210.  At  creameries  where  both  milk  and  cream  are 
delivered,  somewhat  of  an  injustice  is  done  to  patrons  de- 
livering cream,  by  paying  for  the  amounts  of  butter  fat 
furnished  by  the  different  patrons.     By  multiplying  the 
cream  fat  by  1.03,2  the  value  of  his  products  to  the 
creamery  is  taken  into  proper  account,  and  justice  is 
done  to  all  parties  concerned3  (239). 

211.  Gathering      and      sampling      hand-separator 
cream.     On  account  of  the  great  variation  in  both  the 
richness  and  the  purity  of  farm  separator  cream  it  has 
been  found  in  practice  that  composite  samples  of  cream 
are  not  so  satisfactory  to  either  buyer  or  seller  as  the 
testing  of  a  sample  taken  from  each  lot  of  cream  gath- 
ered.    A  still  more  satisfactory  method  is  to  provide 
separate  cans  for  each  patron,  the  cream  gatherer  leav- 

1  Bull.  8  (8.  8.),  Maine  experiment  station. 

2  Splllman  (Dairy  and  Creamery,  Chicago,  April  1, 1899)  recommends 
the  use  of  the  factor  1.044. 

3  This  subject  Is  discussed  in  detail  In  the  17h  annual  report  of  Wls. 
experiment  station,  pp.  90-92;  see  also  the  20th  report  of  this  Station, 
pp.  130-31. 


Testing  Cream  at  Creameries.  185 

ing  an  empty,  clean  can  at  each  farm  and  taking  a  full 
or  partially  filled  can  of  cream  from  the  farm  to  the 
factory.  This  makes  it  necessary  for  the  cream  gath- 
erer to  carry  as  many  cans  as  he  has  patrons  to  gather 
cream  from,  but  it  gives  the  factory  receiving  the  cream 
a  chance  to  inspect,  weigh  and  sample  the  cream  from 
each  farm  and  relieves  the  cream  gatherer  of  all  these 
details  which  are  often  the  cause  of  dissatisfaction. 

Questions. 

1.  In    what   ways   do    the   results   obtained    with    the    oil- test 
churn  differ  from  those  obtained  with  the  Babcock  test? 

2.  Describe  the  method  of  testing  cream  by  the  Babcock  test 
at  gathered- cream  factories. 

3.  What   advantages  has.  the  gathering  of  cream  in  separate 
cans  over  mixing  the  cream  from  all  the  patrons  of  one  route? 


CHAPTER  XII. 
CALCULATION  OF  BUTTER-  AND  CHEESE  VIELD 

A.— CALCULATION  OF  YIELD  OF  BUTTER. 

212.  Butter-fat  test  and  yield  of  butter.  The  Bab- 
cock  test  shows  the  amount  of  pure  butter  fat  contained 
in  a  sample  of  milk,  cream  or  other  dairy  products. 
The  butter  obtained  by  churning  cream  or  milk  con- 
tains, in  addition  to  pure  butter  fat,  a  certain  amount 
of  water,  salt  and  curd.  While  an  accurate  milk  test 
gives  the  total  quantity  of  butter  fat  found  in  the  sam- 
ple of  milk  or  cream  tested,  the  churn  cannot  be  de- 
pended upon  either  to  leave  the  same  amount  of  butter 
fat  in  the  butter  milk  or  to  include  the  same  amount  of 
water,  salt  and  curd  in  the  butter  at  each  churning. 

If  a  quantity  of  milk,  say  3,000  Ibs.,  be  thoroughly 
mixed  in  a  vat,  and  then  divided  into  half  a  dozen  equal 
portions,  a  Babcock  test  of  the  different  lots  will  show 
the  same  percentage  of  butter  fat  in  each  portion.  If, 
on  the  other  hand,  each  of  these  lots  be  skimmed,  and 
the  cream  ripened  in  different  vats  and  churned  sepa- 
rately, the  same  weight  of  butter  from  each  lot  of  500 
Ibs.  of  milk  will  not  be  obtained,  even  by  the  most  expert 
butter  maker,  or  if  all  the  operations  of  skimming,  cream 
ripening,  churning,  salting  and  butter-working  were 
made  as  nearly  uniform  as  possible.  Careful  operators 
can  handle  the  milk  and  cream  so  that  very  nearly  the 
same  proportion  of  fat  contained  in  the  milk  is  re- 


Calculation  of  Butter-  and  Cheese  Yield.       187 


covered  in  the  butter  in  different  churnings,  but  since 
the  water  and  salt  in  butter  are  held  mechanically  and 
are  not  chemically  combined  with  it,  the  amounts  re- 
tained by  the  butter  are  quite  variable  in  different 
churnings,  especially  since  the  laws  governing  the  reten- 
tion of  water  in  butter  are  but  imperfectly  understood. 
213.  Variations  in  the  composition  of  butter.  As 
an  illustration  of  the  variations  in  the  composition  of 
butter  that  usually  occur,  the  analyses  made  in  the 
breed  tests  at  the  World's  Fair  in  1893  may  be  here 
cited;  the  butter  was  in  all  cases  made  by  as  nearly 
identical  methods  and  under  as  uniform  conditions  as 
could  possibly  be  obtained  by  the  skilled  operators  hav- 
ing this  work  in  charge ;  the  average  composition  of  350 
samples  of  this  butter,  with  upper  and  lower  limits, 
was  as  shown  in  the  following  table : 

Composition  of  samples  of  butter,  World's  Fair,  1893. 


Sum  of 

Water. 

Fat. 

Ourd. 

Salt  and 
ash. 

water,c'rd 
salt  and 

ash, 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Average    of   350 

analyses  

11.57 

84.70 

.95 

2.78 

15.30 

Lower   and   up- 

per limits  

8.63-15.00 

76.53-88.26 

.50-2.14 

1.01-8.58 

Analyses  of  fifty  samples  of  creamery  butter  taken  in 
1896,  from  the  tubs  ready  for  market  at  as  many  Wis- 
consin creameries,  showed  that  no  two  of  them  were  ex- 
actly alike  in  composition,  but  varied  within  the  limits 
given  below:1 

1  Wisconsin  experiment  station,  bull.  56. 


188  Testing  Milk  and  Its  Products. 

Summary  of  analyses  of  Wisconsin  creamery  butter. 


Water. 

Fat. 

Curd. 

Salt  and 
ash. 

Sum  of 
water,  curd, 
salt  and 
ash. 

Highest 

Per  cent. 

17  03 

Per  cent. 

87  50 

Per  cent. 
2  45 

Per  cent. 
4  73 

Per  cent. 
22  95 

Lowest 

9  18 

77  07 

36 

1  30 

12  50 

Average  

12.77 

83.08 

1  28 

2  87 

16  92 

The  preceding  analyses  show  the  composition  of  but- 
ter made  at  one  place  where  every  possible  effort  was 
taken  to  produce  a  uniform  product,  and  of  butter  made 
at  fifty  different  creameries,  where  there  was  more  or 
less  variation  in  the  different  operations  of  manufacture 
and  in  the  appliances  and  machinery  used.  The  ma- 
jority of  thesamples  of  butter  analyzed,  in  either  case, 
were  very  near  the  average  composition  given,  but  since 
there  are  such  wide  variations  in  the  composition  of  the 
butter  made  by  the  uniform  methods  adopted  in  the 
World's  Fair  breed  tests,  butter  of  a  more  uniform  com- 
position cannot  be  expected  from  the  thousands  of  dif- 
ferent creameries  and  private  dairies  which  supply  the 
general  market  with  butter. 

The  analyses  of  the  fifty  samples  of  creamery  butter, 
given  above,  show  that  the  content  of  the  butter  fat 
varied  from  77  to  over  87.5  per  cent.,  and  according  to 
the  average  of  the  analyses,  83  pounds  of  butter  fat  was 
contained  in,  or  made,  100  Ibs.  of  butter.     There  was, 
therefore,  in   this   case  produced  20.5  per  cent,   more 
butter  than  there  was  butter  fat,  since 
83 : 100 :  :  100  :  x ;  therefore 
100X100 


83 


-  =  120.5. 


Calculation  of  Butter-  and  Cheese  Yield.        189 

214.  "Overrun"  of  churn  over  test.     The  yield  of 
butter  is  not,  however,  as  a  rule   compared   with  the 
amount  of  butter  fat  contained  in  the  butter,  but  with 
the  total  butter  fat  of  the,  whole  milk  or  cream  from 
which  it  was  made.     This  "increase  of  the  churn  over 
the  test"  is  what  is  generally  called  overrun  in  cream- 
eries. 

The  overrun  obtained  in  different  creameries,  or  even 
in  the  same  creameries  at  different  times,  will  be  found 
to  vary  considerably.  When  the  milk  is  accurately 
tested  and  the  butter  well  worked,  this  overrun  will  vary 
from  10  to  16  per  cent. ;  that  is,  if  a  quantity  of  milk 
contains  exactly  100  Ibs  of  butter  fat,  as  found  by  the 
Babcock  test  or  any  other  accurate  method  of  milk  test- 
ing, from  110  to  116  Ibs.  of  butter  ready  for  market  may 
be  obtained  from  it.  The  overrun  from  cream  will  be 
somewhat  larger,  18  to  22  per  cent.,  but  will  never  ex- 
ceed 25  per  cent.,  unless  the  butter  contains  less  than 
80  per  cent,  fat  (217). 

215.  Factors   influencing  the   overrun  from    milk. 
Even  under  the  very  best  of  care  and  attention  to  de- 
tails, variations  will  occur  in  the  speed  of  the  separator, 
in  the  conduct  of  the  ripening  and  churning  processes, 
and  in  the  condition  of  the  butter  when  the  churn  is 
stopped ;  hence  absolutely  uniform  losses  of  fat  in  skim 
milk  and  butter  milk,  or  the  same  water-  and  salt  con- 
tents of  the  butter,  cannot  be  expected. 

The  overrun  in  separator  creameries  is  influenced  by 
two  legitimate  factors :  first,  the  losses  of  butter  fat  sus- 
tained in  separating  the  milk  and  churning  the  cream, 
and  second,  the  gain  due  to  the  admixture  of  water, 


190  Testing  Milk  and  Its  Products. 

salt,  etc.,  in  the  manufacture  of  butter.  Considering 
first  the  losses  of  fat  in  skim  milk  and  butter  milk,  the 
separator  will  usually,  when  run  at  normal  speed  and 
capacity,  leave  the  same  per  cent,  of  fat  in  skim  milk, 
whether  rich  or  poor  milk  is  skimmed.  An  exception 
to  this  may  be  found  in  separating  rich  milk  having 
large  fat  globules,  or  milk  from  fresh  milkers,  in  either 
of  which  cases  the  large  size  of  the  fat  globules  occa- 
sions a  more  complete  separation  of  fat  by  the  centri- 
fugal force.  But  generally  speaking,  the  statement 
holds  good  that  the  total  loss  of  fat  in  separator  skim 
milk  is  a  factor  of  the  quantity  of  milk  run  through  the 
separator,  rather  than  of  its  quality.  It  follows  from 
this,  however,  that  the  relative  losses  of  fat  in  skim  milk 
will  vary  to  some  extent  according  to  the  quality  of  the 
milk  separated.  Selecting  two  extremes  in  the  quality 
of  milk,  2.5  and  6.0  per  cent,  of  fat,  there  will  be  found, 
say  .1  per  cent,  of  fat  in  the  skim  milk  from  either  lot, 
provided  the  separator  is  not  unduly  crowded,  and  the 
separation  is  conducted  under  normal  conditions  in  each 
case.  But  .1  per  cent,  fat  makes  4  per  cent,  of  the  total 
fat  in  the  poor  milk  (  ii^|  -  =4) ,  and  only  1.7  per  cent, 
of  that  in  the  rich  milk.  It  takes  4000  Ibs.  of  the  2.5 
per  cent,  milk  to  furnish  100  Ibs.  of  fat,  and  only  1666 
Ibs.  cf  the  6  per  cent,  milk ;  in  skimming  the  poor  milk, 
a  less  of  .1  per  cent,  of  fat  is  sustained  in  the  skim  milk 
from  4000  Ibs.  of  milk  (3.4  Ibs.  fat),  while  in  the  rich 
milk  n  similar  loss  is  sustained  in  the  skim  milk  from 
only  1666  Ibs.  of  milk  (1.4  Ibs.  fat). 


Calculation  of  Butter-  and  Cheese  Yield.        191 

The  example  gives  an  extreme  case,  and  one  not  likely 
to  be  met  with  in  practice.  The  range  of  the  richness  of 
the  milk  delivered  by  different  patrons  at  the  factory  is 
usually  within  one-half  or  one  per  cent,  of  fat.  In  such 
cases  the  proportion  cf  fat  lost  in  skimming  does  not 
vary  much,  e.  g.,  in  case  of  milk  containing  3.5  and  4.0 
per  cent,  of  fat,  and  variations  in  the  overrun  occurring 
when  the  proper  care  in  skimming,  ripening  and  churn- 
ing is  taken,  are  due,  therefore,  primarily  to  differences 
in  the  water  and  salt  contents  of  the  butter  made  (204). 

216.  The  losses  from  poor,  rich  and  average  milk,  as 
received  at  creameries  and  cheese  factories,  can  be  traced 
from  the  following  statement ;  this  gives  the  quantities 
of  fat  lost  in'  handling  milk  of  four  grades,  viz. :  2.5, 
3.5,  4.0  and  6.0  per  cent.,  in  case  of  each  grade  calcu- 
lated to  a  standard  of  100  Ibs.  of  fat  in  the  milk. 

To  supply  100  Ibs.  of  fat  would  require  the  following 
amounts  cf  the  different  grades  of  milk: 

4000  Ibs.  of  milk  testing  2.5  per  cent,  will  contain  100  Ibs.  of  fat. 

2857  "     "  "       3.5         "         .    "         "         100     <4  "      " 

2500  "     "  "       4.0         "  "         "         100     "  "      " 

1666  "     "  il       6.0         "  "         "         100     "  "      " 

Assuming  that  the  skim  milk  contains  .1  per  cent,  of 
fat  and  makes  up  85  per  cent,  of  the  whole  milk,  and 
that  the  butter  milk  tests  .3  per  cent.,  and  forms  10 
per  cent,  of  the  whole  milk,  the  butter-fat  record  of 
the  quantities  of  different  grades  of  milk  containing  100 
Ibs.  of  fat  will  be  as  given  in  the  following  table.  Cer- 
tain mechanical  losses  are  unavoidable  in  the  cream- 
ery, as  in  all  other  factory  operations,  viz.,  milk  and 
cream  remaining  in  vats  and  separators,  butter  sticking 


192 


Testing  Milk  and  Its  Products. 


to  the  walls  of  the  churn,  etc.  These  losses  have  been 
found  to  average  about  3  per  cent,  of  the  total  fat  in 
the  milk  handled,  under  normal  conditions  and  under 
good  management  (219). 

Fat  available  for  butter  in  different  grades  of  milk. 


Grade  of  milk. 

Whole 
milk. 

Skim 
milk. 

Butter 
milk. 

Waste 

Total 
loss. 

Fat. 

availa- 
ble for 
butter. 

2.5  percent  

4000  Ibs. 
2.5  per  ct. 

3400  Ibs. 
.1  per  ct. 

400  Ibs. 
.3  per  ct. 

Ibs. 

Ibs. 

Per  ct. 

Fat  

100  Ibs. 

3.4  Ibs. 

1.2  Ibs. 

3.0 

7.6 

92.4 

3.5  per  cent  

2857  Ibs. 
3.5  per  ct. 

2429  Ibs. 
.1  per  ct. 

286  Ibs. 
.3  per  ct. 

Fat... 

100  Ibs. 

2.4  Ibs. 

.91b. 

3.0 

6.3 

93.7 

4.0  per  cent  

2500  Ibs. 
4  per  ct. 

2125  Ibs. 
.1  per  ct. 

250  Ibs. 
.3  per  ct. 

Fat... 

100  Ibs. 

2.1  Ibs. 

.7  Ib. 

3.0 

5.8 

94.2 

6.0  per  cent  

1666%  Ibs. 
6  per  ct. 

1417  Ibs. 
.1  per  ct. 

167  Ibs. 
.3  per  ct. 

Fat  

100  Ibs. 

1.4  Ibs. 

.5  Ib. 

3.0 

4.9 

95.1 

The  table  shows  that  with  2.5  per  cent.-milk,  there  is 
a  loss  of  3.4  Ibs.  of  fat  in  the  skim  milk,  a  loss  of  1.2 
Ibs.  of  fat  in  the  butter  milk,  and  of  3.0  Ibs.  in  the 
creamery  waste,  for  every  100  Ibs.  of  fat  in  the  whole 
milk,  or  a  total  loss  of  7.6  Ibs.  from  these  sources.  In 
case  of  6  per  cent,  milk  these  losses  are  1.4  Ibs.,  .5  Ib. 
and  3.0  Ibs.  for  skim  milk,  butter  milk  and  waste  re- 
spectively; a  total  loss  of  4.9  Ibs.,  or  2.7  Ibs.  less  than 
the  losses  with  poor  milk.  This  difference  in  the  losses 
shrinks  to  only  .5  pound  of  fat  in  case  of  3.5  and  4.0 
per  cent.-milk,  when  a  quantity  containing  100  Ibs.  of 
fat  is  handled  in  both  cases. 


Calculation  of  Butter-  and  Cheese  Yield.        193 

The  overrun  from  each  of  the  four  grades  of  milk  can 
be  calculated  for  butter  containing  a  certain  per  cent, 
of  fat.  Assuming  the  fat  content  of  butter  to  be  83  per 
cent,  on  the  average  (213),  the  quantity  of  butter  ob- 
tained from  the  100  Ibs.  of  fat,  or  rather  from  the  por- 
tion thereof  which  is  available  for  butter,  in  each  ease 
will  be  as  follows : 

100  fts.  of  fat  from  Available    Butter  cont.^  Overrun 

4,000  ft s.  of  2.5  per  cent.  milk. . . .  92.4  fts.=  111.3  fts.  11.3 

2,857  fts.  of  3.5  per  cent,  milk 93.7  fts.=  113.0  fts.  13.0 

2,500  fts.  of  4.0  per  cent,  milk 94.2  fts.=  113.5  fts.  13.5 

1,666  Ibs.  of  6.0  per  cent,  milk 95.1  fts.=  114.6  fts.  14.6 

All  butter  makers  should  obtain  more  butter  from  a 
certain  quantity  of  milk  than  the  Babcock  test  shows  it 
to  contain  butter  fat,  but  it  is  impossible  to  know  ex- 
actly, except  by  chemical  analysis,  how  much  butter  fat 
is  lost  in  the  skim  milk  and  the  butter  milk,  and  how 
much  water,  salt  and  curd  the  butter  will  contain. 

217.  Overrun  from  cream.  The  overrun  from  cream 
is,  as  already  stated,  larger  than  from  milk  because 
there  is  no  loss  of  fat  in  the  skim  milk  to  be  consid- 
ered. Rich  cream  will  give  a  somewhat  greater  over- 
run than  thin  cream,  for  the  same  reasons  as  have  been 
shown  in  the  calculations  of  overrun  from  milk.  If 
similar  calculations  are  made  from  cream  of  different 
richness  as  these  given  for  milk  (216),  the  fat  available 
for  butter-making  and  the  yield  of  butter  per  100  pounds 
of  fat  in  the  cream  will  be  as  shown  below.  A  loss 
through  waste  in  the  process  of  butter-making  amount- 
ing to  2  per  cent,  has  been  assumed  in  these  calcula- 
tions : 

13 


194 


Testing  Milk  and  its  Products. 


100  Ibs.  fat  in 

Available  fat, 

Butter  of 

QQC/f,    fni 

Overrun, 

cream 

Ibs. 

Ibs. 

per  cent. 

20% 

96.8 

116.6 

16.6 

30% 

97.3 

117.2 

17.2 

40% 

97.6 

117.6 

17.6 

We  note  that  the  overrun  for  cream  of  different  qual- 
ity under  the  conditions  given  ranges  from  16.6  to  20- 
per  cent,  cream  to  17.6  for  40-per  cent,  cream.  A  some- 
what larger  overrun  would  be  obtained  when  the  butter 
made  contains  less  fat  and  more  water  than  assumed. 

Assuming  that  the  butter  contains  the  maximum 
amount  of  water  allowed  by  law  (16  per  cent.)  and 
nearly  80  per  cent,  fat,  the  overrun  for  both  milk  and 
cream  would  be  somewhat  larger  than  already  given,  as 
shown  by  the  following  figures: 

Maximum  overrun  from  milk         Maximum  overrun  from  cream 


2  5% 

15  5 

20% 

21.0 

3.5%    

17.1 

30%  

21.6 

4.0%  
6.0%.  ../.. 

17.8 
18.9 

40  %  

22.0 

This  table  shows  the  highest  overruns  that  are  likely 
to  be  obtained  when  the  cream  is  to  contain  no  more 
than  the  maximum  amount  of  water  allowed  by  law. 
Larger  overruns  can  only  be  obtained  by  reducing  the 
losses  of  manufacture  (which  will  give  but  slightly 
higher  figures)  or,  fraudulently,  by  inaccurate  weigh- 
ing or  testing  of  the  milk,  cream  or  butter. 

218.  Calculation  of  overrun.  The  overrun  is  calcu- 
lated by  subtracting  the  amount  of  butter  fat  contained 
in  a  certain  quantity  of  milk  or  cream,  from  the  amount 


.. 

Calculation  of  Butti^and  Cheese  Yield. 

of  butter  made  from  it,  and  iindmg  ^fiat^ter.  cent,  this 
difference  is  of  the  amount  of  butter  fat  in  the  milk. 

Example  1  :  8000  Ibs.  of  milk  is  received  at  the  creamery  on 
a  certain  day;  the  average  test  of  the  milk  is  3.8  per  cent.  By 
a  simple  multiplication  we  find  that  thd  milk  contained  8000  X 
.038=304  Ibs.  of  butter  fat.  340  Ibs.  of  butter  was  made  from 
this  milk,  as  shown  by  the  weights  of  the  packed  tubs.  The  dif- 
ference between  the  weight  of  butter  and  butter  fat  is,  therefore, 
36  Ibs.;  36  is  36tX100  =11.8  per  cent,  of  the  quantity  of  butter 
fat  in  the  milk;  that  is,  the  overrun  for  the  day  considered  was 
11.8  per  cent. 

The  formula  for  the  overrun  is  as  follows  : 
v_(b—  f)  100 

~T~  -r.aaa 

b  and  /  designating  the  quantities  of  butter  and  butter 

fat,  respectively,  made  from  or  contained  in  a  certain 
quantity  of  milk.  In  the  preceding  example,  the  calcu- 
lation would  be  as  follows:  (340-aoi)xioo=ii<8  per  cent. 

804 

Example  2:  1000  Ibs.  of  cream  testing  25  per  cent,  fat  con- 
tains 1000  X.  25=250  Ibs.  butter  fat.  If  304  Ibs.  of  butter  is 
made,  the  overrun  may  be  calcullated  by  subtracting  the  butter 
fat  from  the  butter,  304—250=54  Ibs.,  'then  divide  this  by  the 


fat  in  the  cream  and  multiply  by  100;   or  ^2^=18  per  cent., 

oOO 

which  is   the  cream  overrun. 

219.  Conversion  factor  for  butter  fat.  A  committee 
of  the  Association  of  American  Agricultural  Colleges 
and  Experiment  Stations  at  the  ninth  annual  convention 
of  the  Association  reported  that  "in  the  ninety-day 
Columbian  Dairy  Test,  96.67  per  cent,  of  the  fat  in  the 
whole  milk  was  recovered  in  the  butter.  This  butter,  on 
the  average,  contained  82.37  per  cent,  butter  fat;  in 
other  words,  117.3  pounds  of  butter  were  made  from 
each  100  pounds  of  butter  fat  in  the  whole  milk.1  The 

1  When  82.37  Ibs.  of  butter  fat  will  make  100  lt>s.  of  butter,  how  much 
butter  will  96.«7  tt>s.  of  butter  fat  make?    82.37:96.67:  :  100  :x,  x=  117.3. 


196  Testing  Milk  and  Its  Products. 

exact  conversion  factor  would  be  1.173.  As  this  is  an 
awkward  number  to  use,  and  as  1%  is  so  nearly  the 
same  ...  it  has  seemed  best  to  recommend  that  the 
latter  be  used  as  the  conversion  f actor, " 

A  resolution  was  adopted  by  this  Association  recom- 
mending that  the  approximate  equivalent  of  butter  be 
computed  by  multiplying  the  amount  of  butter  fat 
by  1%,  and  this  figure  has  been  generally  accepted  for 
computing  the  yield  of  butter  from  a  certain  amount  of 
butter  fat. 

The  figures  given  are  the  result  of  more  than  ordinary 
care  in  skimming,  churning  and  testing,  and  probably 
represent  the  minimum  losses  of  fat  in  the  manufactur- 
ing processes.  The  increase  of  churn  over  test  repre- 
sented by  one-sixth,  or  16  per  cent.,  may  therefore  be 
taken  as  a  maximum  "overrun"  for  milk  under  ordi- 
nary factory  conditions. 

220.  Butter  yield  from  milk  of  different  richness. 
a.  Use  of  butter  chart.  The  approximate  yield  of  but- 
ter from  milk  of  different  richness  is  shown  in  Table  XI 
in  the  Appendix.  This  table  is  founded  on  ordinary 
creamery  experience  and  will  be  found  to  come  near  to 
actual  every-day  conditions  of  creameries  where  modern 
methods  are  followed  in  the  handling  of  the  milk  and 
its  products.  The  table  has  been  prepared  in  the  fol- 
lowing manner: 

It  is  assumed  that  the  average)  loss  of  fat  in  the  skim  milk  is 
.20  per  cent.,  and  that  85  Ibs.  of  skim  milk  is  obtained  from  each 
100  Ibs.  of  whole  milk;  to  this  loss  of  fat  is  added  that  from 
the  butter  milk;  about  10  Ibs.  of  butter  milk  is  obtained  per  100 
Ibs.  of  whole  milk,  testing  on  the  average  .30  per  cent. 

If  f  designate  the  fat  in  100  Ibs.  of  milk,  then  the  fat  recov- 
ered in  the  butter  from  100  Ibs.  of  milk  will  be 


Calculation  of  Butter-  and  Cheese  Yield        197 


There  is,  on  the  other  hand,  an  increase  in  weight  in  the  but-- 
ter    made,    owing    to    the    admixture    of    non-fatty    components 
therein,    principally    water    and    salt.     Butter   packed    and   ready 
for  the  market  will  contain  in  the  neighborhood  of  84  per  cent. 
of  fat  (214),  so  that  the  fat  recovered  in  the  butter  must  be  in- 
creased by  i^0—  1.19.     If  B  therefore  designate  the  yield  of  but- 
ter from  100  Ibs.  of  milk,  the  following  formula  will  express  the 
relation    between   yield   and   fat   content,    provided   there   are   no 
other   factors  entering  into   the   problem,   viz.: 
B=(f—  .20)   1.19 

From   this   value   for    B,    should  be    deducted    the   loss   due   to 
wastes  in  thet  manufacturing  processes,  amounting  to  3  per  cent. 
of  the  total  fat  in  the  milk  handled,  and  we  therefore  have: 
B=(f—  .20)    1.16 

Since  this  table  is  based  on  a  fat  content  of  .2  per 
cent,  in  the  skim  milk,  the  figures  for  the  overrun  are 
slightly  lower  than  may  be  obtained  in  creameries  pro- 
vided with  up-to-date  cream  separators. 

221.  Table  XI  in  the  Appendix,  founded  on  this 
formula,  may  be  used  to  determine  the  number  of 
pounds  of  butter  which  milk  containing  3  to  5.3  per 
cent,  fat  will  be  likely  to  make.  It  presupposes  good 
and  careful  work  at  the  separator,  churn  and  butter 
worker,  and  under  such  conditions  will  generally  show 
yields  of  butter  varying  but  little  from  those  actually 
obtained.  It  may  be  conveniently  used  by  the  butter 
maker  or  the  manager  to  check  up  the  work  in  the 
creamery;  the  average  test  of  the  milk  received  during 
a  certain  period  is  found  by  dividing  the  total  butter 
fat  received,  by  the  total  milk,  and  multiplying  the 
quotient  by  100  ;  the  amount  of  butter  which  the  total 
milk  of  this  average  fat  content  will  make,  according  to 
the  table,  is  then  compared  with  the  actual  churn  yield. 


198  Testing  Milk  and  Its  Products. 

Example:  A  creamery  receives  200,000  Ibs.  of  milk  during 
a  month ;  the  milk  of  each  patron  is  tested  and  the  fat  contained 
therein  calculated.  The  sum  of  these  amounts  of  fat  may  be 
7583  Ibs;  the  average  test  of  the  milk  is  then  3.79  per  cent.  Ac- 
cording to  Table  XI,  10,000  Ibs.  of  milk,  testing  3.8,  will  make 
418  Ibs.  of  butter,  and  200,000  Ibs.,  therefore,  8360  Ibs.  of  but- 
ter. The  total  quantity  of  butter  made  during  the  month  will 
not  vary  appreciably  from  this  figure  if  the  work  in  the  cream- 
ery has  beien  properly  done. 

222.  b.  Use  of  overrun  table.    The  table  referred  to 
above  gives  a  definite  calculated  butter  yield  for  each 
grade  of   milk,   according  to  average  creamery  condi- 
tions.    As  it  may  be  found  that  this  table  will  give  uni- 
formly either  too  low  or  too  high  results,  Table  XII  in 
the  Appendix  is  included,  by  means  of  which  the  butter 
yield  corresponding  to  overruns  from  10-20  per  cent, 
may  be  ascertained  in  a  similar  way  as  above  described. 

The  total  yield  of  butter  is  divided  by  the  total  num- 
ber of  pounds  of  fat  delivered;  the  quotient  will  give 
the  amount  of  butter  made  from  one  pound  of  fat,  and 
this  figure  multiplied  by  the  fat  delivered  by  each  pat- 
ron shows  the  pounds  of  butter  to  be  credited  to  each 
patron.  To  use  the  table,  find  in  the  upper  horizontal 
line  the  number  corresponding  nearest  to  the  number  of 
pounds  of  butter  from  one  pound  of  fat.  The  vertical 
column  in  which  this  falls  gives  the  pounds  of  butter 
from  100  Ibs.  of  milk  containing  the  per  cents,  of  fat 
given  in  the  outside  columns  (Babcock). 

B.— CALCULATION  OP  YIELD  OP  CHEESE. 

223.  a.  From   fat.    The  approximate  yield  of  green 
Cheddar  cheese  from  100  Ibs.  of  milk  may  be  found  by 
multiplying  the  per  cent,  of  fat  in  the  milk  by  2.7 ;  if  / 


Calculation  of  Butter-  and  Cheese  Yield.        199 

designate  the  per  cent,  of  fat  in  the  milk,  the  formula 
will,  therefore,  be: 

Yield  of  cheese=2.7  f (I) 

The  factor  2.7  will  only  hold  good  as  the  average  of  a 
large  number  of  cases.  In  extensive  investigations  dur- 
ing three  consecutive  years,  Van  Slyke*  found  that  the 
number  of  pounds  of  green  cheese  obtained  for  each 
pound  of  fat  in  the  milk  varied  from  2.51  to  3.06,  the 
average  figures  for  the  three  years  1892- '94,  inclusive, 
being  2.73,  2.71,  and  2.72  Ibs.,  respectively.  The  richer 
kinds  of  milk  will  produce  cheese  richer  in  fat,  and 
will  yield  a  relatively  larger  quantity  of  cheese,  pound 
for  pound,  than  poor  milk,  for  the  reason  that  an  in- 
crease in  the  fat  content  of  milk  is  accompanied  by  an 
increase  in  the  other  cheese-producing  solids  of  the 
milk.2  The  preceding  formula  would  not,  therefore,  be 
correct  for  small  lots  of  either  rich  or  poor  milk,  but 
only  for  milk  of  average  composition,  and  for  large 
quantities  of  normal  factory  milk.  For  cured  cheese 
the  factor  will  be  somewhat  lower,  viz.,  about  2.6,  on 
the  average. 

224.  b.  From  solids  not  fat  and  fat.  If  the  percent- 
ages of  solids  not  fat  and  of  fat  in  the  milk  are  known, 
the  following  formula  by  Babcock  will  give  close  results : 

Yield  of  green  cheo?=1.58  (f +.91  f)      .       .       (II) 

1  N.  Y.  experiment  station  (Geneva),  bulletins  65  and  82. 

2  Investigations  as  to  the  relation  between  the  quality  of  the  milk 
and  the  yield  of  cheese  have  been  conducted  by  a  number  of  experi- 
ment stations;  the  following  references  give  the  main  contributions 
published  on  this  point;  N.  Y.  (Geneva)  exp.  station,  reports  10-18,  inch; 
Wis.  exp.  sta.,  reports  11  and  12;  Ont.  Agr.  College,  reports  1894-'96,  incl.; 
Minn.  exp.  sta.,  b.  19,  reports  1892-'94,  incl.;   Iowa  exp.  sta.,  bull.   21; 
Hoard's  Dairyman,  1892,  p.  2400. 


200  Testing  Milk  and  Its  Products. 

s  being  the  per  cent,  of  solids  not  fat  in  the  milk,  and  / 
the  per  cent,  of  fat.1 

The  solids  not  fat  can  be  readily  ascertained  from  the 
lactometer  reading  and  the  per  cent,  of  fat,  as  shown  on 
p.  106,  by  means  of  Table  VI  in  the  Appendix. 

Table  XIII  in  the  Appendix  gives  the  yield  of  cheese 
from  100  Ibs.  of  milk  containing  from  2.5  to  6.0  per 
cent,  fat,  the  lactometer  readings  of  which  range  be- 
tween 26  and  36.  By  means  of  this  table  cheese  makers 
can  calculate  very  closely  the  yields  of  cheese  which 
certain  quantities  of  milk  will  make;  as  it  takes  into 
consideration  the  non-fatty  solids  as  well  as  the  fat  of 
the  milk,  the  results  obtained  by  the  use  of  this  formula 
will  be  more  correct  than  those  found  by  means  of 
formula  (I).  The  uncertain  element  in  the  formula  lies 
in  the  factor  1.58,  which  is  based  on  an  average  water 
content  of  37  per  cent,  in  the  green  cheese.  This  may, 
however,  be  changed  to  suit  any  particular  case,  e..g., 
35  per  cent.  (^^1.54),  40  per  cent.  yV°=l-67,  etc. 
The  average  percentages  of  water  in  green  cheese  found 
by  Van  Slyke  in  his  investigations  referred  to  above, 
were  for  the  years  1892- '94,  respectively,  36.41,  37.05 
and  36.70  per  cent. 

225.  c.  From  casein  and  fat.  If  the  percentages  of 
casein  and  fat  in  the  milk  are  known,  the  yield  of  cheese 
may  be  calculated  by  the  following  formula,  also  pre- 
pared by  Dr.  Babcock: 

Yield  of  cheese=l.l  f+2.5  casein     ....    (III). 

This  formula  will  give  fairly  correct  results,  but  no 
more  so  than  formula  (II)  ;  it  is  wholly  empirical. 

l  For  derivation  of  this  formula,  see  Wisconsin  experiment  station. 
twelfth  report,  p.  105. 


Calculation  of  Butter-  and  Cheese  Yield.        201 

Questions. 

1.  What    is    the    average    composition    of    American    creamery 
butter,  and  between  what  extremes  does  the  composition  of  butter 
vary  ? 

2.  What  is  the  difference  between  the  churn  yield  and  the  re- 
sults obtained  by  the  Babcock  test? 

3.  What  does  the  overrun  represent? 

4.  Mention  several  factors  that  cause  a  large  overrun. 

5.  Give   an   illustration   of  how   the   per   cent,   of   increase   of 
churn  over  test  is  found,  and  how  the  overrun  is  calculated. 

6.  Show  by  an  example  that  butter  containing  20%  fat   can- 
not give  an  overrun  of  more  than  25%. 

7.  How   many   pounds   of   butter   containing   80%    fat  can  be 
made   from    100*  Ibs.    fat? 

8.  Why  is  the  overrun  from  cream  greater  than  from  milk? 

9.  What   is   the   overrun   when   70.5   Ibs.   of  butter    are   made 
from  140  Ibs.  of  milk,  testing  3.15  per  cent? 

10.  What   is  the   overrun   in  each   of  the  following   cases? 

220  Ibs.  butter  from  8000  Ibs.  milk,  testing  2.3%  fat. 
250  Ibs.  butter  from  4000  Ibs.  milk,  testing  5.8%  fat. 
600  Ibs.  butteir  from  2000  Ibs.  cream,  testing  25.0%  fat. 
480  Ibs.  butter  from  1000  Ibs.  cream,  testing  40.0%  fat. 

11.  How  much  butter  containing  (a)   80%  fat    and   (b)   82.5% 
fat  can  be  made  from  3250  Ibs.  milk,  testing  4.3%   fat,   assum- 
ing that  the  skim  milk  is   80%   of   the  whole  milk  and   contains 
0.1%  fat,  and  the  butter  milk,  which  is  the  cream  minus  the  fat, 
contains  0.25%  fat?     What  is  the  overrun  in  each   case? 

12.  How  much  butter  is  obtained  from  5800  Ibs.  milk,   testing 
3.7%  fat,  when  the  overrun  is   (a)   125%   and   (b)    16%? 

13.  Two  cows  in  full  milk  produce,  one  17.5  Ibs.  of  milk  a  day, 
containing  4.35%  fat;   the  other.  27.3  Ibs.  of  milk,  testing  3.4%. 
If  the  milk  of  both  is  made  into  butter  or  cheese,  what  may  be 
expected  from  each  one  in  a  week? 

14.  What  is   a   fair  percentage  of  loss  of  fat  by   waste  other 
than  in  skim  milk  and  butter  milk  under  average  creamery  con- 
ditions? 

15.  How  much  butter  may  be  made  from    (a)   15,640  Ibs.  milk, 
testing   3.8%    fat,   and    (b)    35  842   Ibs.   milk,   testing   4.1%    fat? 
(Use  Table  XT,  Appendix.} 

16.  How    can   the   per    cent,    of    fat    in   butter   be    determined 
without  making  a  test  of  it? 

17.  How  may  the  yield  of  cheese  from  milk  of  any  known  test 
be  approximately  calculated? 

18.  How  many  pounds  of  cheese  can  be  made  from  3570  Ibs. 
milk,   testing  3.5%   fat   and  having  a  lactometer  reading  of  32  5 
at  67°  F.?     (Use  Table  XIII,  Appendix.) 


CHAPTEE  XIII. 
CALCULATING  DIVIDENDS. 

226.  The  simplest  method  of  calculating  dividends  at 
creameries  is  to  base  the  calculations  on  the  amount  of 
butter  fat  delivered  by  the  various  patrons.     Each  lot 
of  milk  is  weighed  when  delivered  at  the  creamery,  and 
a  small  quantity  thereof  is.  saved  for  the  composite  sam- 
ple,   as    previously    explained    under    Composite  Tests 
(180).     Some  creameries  test  these  samples  at  the  end 
of  each  week,  and  others  after  collecting  them  for  ten 
days  or  two  weeks.     If  the  four  weekly  composite  sam- 
ples of  a  patron's  milk  tested  3.8,  4.0,  3.9,  4.1  per  cent , 
these  four  tests  are  added  together,  and  the  sum  divided 
by  4;  the  result,  3.95  per  cent.,  is  used  as  the  average 
test  of  this  milk.     Py  multiplying  the  total  number  of 
pounds  of  milk  delivered  by  this  patron,  by  his  average 
test,  the  total  weight  in  pounds  of  butter  fat  delivered 
to   the    factory    during    the   month    is   obtained.     This 
weight  of  fat  is  then  multiplied  by  the  price  to  be  paid 
by  the  creamery  per  pound  of  butter  fat;  the  product 
shows  the  amount  of  money  due  this  patron  for  the  milk 
delivered  during  the  time  samples  were  taken. 

227.  Price  per  pound  of  butter  fat.     The  method  of 
obtaining  the  price  to  be  paid  for  one  pound  of  butter 
fat  varies  somewhat  in  different  creameries,  on  account 
of  the  different  ways  of  paying  for  the  cost  of  manu- 
facturing  the   hnttor.     The   method   to   be   followed   is 


Calculating  Dividends.  203 

generally  determined  by  agreement  between  the  manu- 
facturer and  the  milk  producers,  in  case  of  proprietary 
creameries,  or  among  the  shareholders,  in  co-operative 
creameries.  The  following  methods  of  paying  for  the 
cost  of  manufacture  are  at  the  present  time  met  with 
in  American  creameries. 

228.  I.  Proprietary  creameries.  First. — When  the 
creamery  is  owned  by  some  one  person  or  company,  the 
owner  or  owners  agree  to  make  the  butter  for  about  3 
cents  a  pound;  the  difference  between  the  total  receipts 
of  the  factory  and  the  amount  due  the  owner  is  then 
divided  between  the  different  patrons,  according  to  the 
amount  of  butter  fat  contained  in  the  milk  which  they 
delivered. 

In  the  majority  of  cases,  the  price  charged  for  making 
butter  is  now  3  cents  a  pound;  2%  and  2y2  cents  are 
sometimes  charged.  The  larger  the  amount  of  milk  re- 
ceived at  a  factory,  the  lower  will  naturally  be  the  cost 
of  manufacturing  the  butter.1 

Second.— The  proprietor  of  the  creamery  sometimes 
agrees  to  pay  a  certain  price  for  100  Ibs.  of  milk  deliv- 
ered, according  to  its  fat  content,  the  price  of  milk  con- 
taining 4  per  cent,  of  butter  fat  being  the  standard. 
This  price  may  change  during  the  different  seasons  of 
the  year  by  mutual  agreement. 

Third.— A  creamery  owner  may  offer  to  pay  1  to  2 
cents,  usually  li/o  cents,  below  the  average  market  price 
of  butter,  for  each  pound  of  butter  fat  received  in  the 
milk. 

1  Bull.  56,  p.  26,  Wisconsin  exp.  station;  see  Report  18,  Iowa  State 
Dairy  Commissioner,  p,  33, 


204  Testing  Milk  and  Its  Products. 

229.  II.  Co-operative  creameries.  In  this  case,  where 
the  creamery  is  owned  by  the  patrons,  one  of  the  stock- 
holders who  is  elected  secretary  attends  to  the  details  of 
running  the  factory  and  selling  the  product.     His  ac- 
counts show  the  amount  of  money  received  each  month 
for  the  butter  and  other  products  sold,  and  the  expenses 
of  running  the  factory  during  this  time.     The  expenses 
are  subtracted  from  the  receipts,   and  the  balance  is 
divided  among  the  patrons,  each  one  receiving  his  pro- 
portionate share  according  to  the  amounts  of  butter  fat 
delivered  in  each  case,  as  shown  by  the  total-  weight  and 
the  average  test  of  milk  delivered  during  this  time. 

In  nearly  all  cases,  the  farmers  receive  about  eighty 
pounds  of  skim  milk  for  each  one  hundred  pounds  of 
whole  milk  they  deliver  to  the  factory,  in  addition  to 
the  amount  received  for  the  milk,  calculated  according 
to  one  or  the  other  of  the  preceding  methods. 

230.  Illustrations  of  calculations  of  dividends.    Tn  order 
to  illustrate  the   details  of   calculating   dividends,   or  the  amount 
to  be  paid  each  patron  for  the  milk  supplied  each  month,  when 
payments  are  made  by  each  of  the  four  systems  given,  it  will  be 
assumed  that  a  creamery  receives  5000  pounds  of  milk  daily  for 
thirty  days,  and  makes  6650  Ibs.  of  butter  from  the  150,000  Ibs. 
of  milk  received  during  this  time.     Thet  average  test  of  this  milk 
may  be  found  by  multiplying  the  total  weight  of  milk  delivered 
by   each   patron  by  his   average  test,   and   dividing  the   sum    of 
those  products  by  the  total  weight  of  milk  received  at  the  cream- 
ery  (in  the  example  given,  by  150.000),  the  quotient  being  mul- 
tiplied by  100.     Such  calculations  may  show  that,  e.  g.,  5700  Ibs. 
of  butter  fat  have  been  received  in  all  the  milk  delivered  by  the 
different  patrons;  this  multiplied  by  100  and  divided  by  150,000 
gives  3.8  as  the  average  test,  or  the  average  amount  of  butter 
fat  in  each  100  Ibs.  of  milk  received  during  the  month. 

So  far  the  method  of  calculation  is  common  for  all  different 
systems  of  payment  given  above;  the  manner  of  procedure  now 


Calculating  Dividends. 


205 


differs  according  to  the  agreement  made  between  owner  and 
patrons,  or  among  the  shareholders,  in  case  of  co-operative 
creameries. 

231.  I.  First. — If  the  net  returns  for  the  6650  Ibs.  of  butter 
sold  during  the  month  were  $1197,  and  the  creamery  is  to  re- 
ceive 4  cents  per  pound  of  butter  as  the  cost  of  manufacture, 
etc.,  the  amount  due  the  creamery  is  6650X.04=$266,  and  the 
patrons  would  receive  $1197— $266=$931.  This  sum,  $931,  is  to 
be  paid  to  the  patrons  for  the  5700  Ibs.  of  butter  fat,  which,  as 
shown  above,  was  the  weight  of  fat  contained  in  the  150,00.0  Ibs. 
of  milk  delivered  during  the  month.  The  price  of  one  pound  of 
butter  fat  is  then  easily  found:  $931-f-5700=16%  cents.  This 
price  is  paid  to  all  patrons  for  each  pound  of  butter  fat  deliv- 
ered in  their  milk  during  the  month.  The  monthly  milk  record 
of  three  patrons  may,  e.  g.,  be  as  given  in  the  following  table: 


First 

Second 

Third 

Fourth 

"M    . 

week 

week 

week 

week 

Tot'l 

*1 

a  o 

Milk 
Ibs. 

Test 
per 
cent. 

Milk 
Ibs. 

Test 
per  ct. 

Milk 
Ibs. 

Test 
per 
cent. 

Milk 
Ibs. 

Test 
per  ct. 

Milk 

Ibs. 

J| 

No.  1 

3500 

3.6 

3000 

3.5 

3600 

3,65 

3450 

3.45 

13,550 

3.55 

No.  2.... 

700 

3.8 

665 

3.8 

720 

3.6 

750 

3.7 

2,825 

3.73 

No.  3.... 

2480 

4.2 

2000 

3.8 

1850 

4.0 

1500 

3.6 

7,830 

3.90 

Multiplying  each  patron >s  total  milk  by  his  average  test  gives 
the  number  of  pounds  of  butter  fat  in  his  milk,  and  this  figure 
multiplied  by  .16%  shows  the  money  due  for  his  milk,  "as  given 
below: 


Patron 

Total 
milk 
Ibs. 

Average 
test, 
per  cent. 

Butter  fat 
tt>s. 

Price  of  fat 
per  lb.,  cents 

Amount 
due 

No.  1... 
No.  2  
No.  3 

13,550 
2,825 
7  830 

3.55 
3.7 
3  9 

481.0 
104.5 
305  4 

16% 
16% 
16  H 

$78.56 
17.06 

48  87 

232.  Second. — When  the  proprietor  of  a  creamery  agrees  to 
pay  a  certain  price  for  100  Ibs.  of  4  per  cent,  milk,  the  receipts 
for  butter  sold  and  the  price  per  pound  of  butter  do  not  enter 
into  the  calculation  of  the  amount  due  each  patron  for  his  milk; 


206 


Testing  Milk  and  Its  Products. 


but  the  weight  and  the  test  of  each  patron's  milk  are  as  im- 
portant as  before.  If  it  is  agreed  to  pay  66  cents  per  100  Ibs. 
of  4  per  cent,  milk  (i.  e.,  milk  containing  4  per  cent,  of  butter 
fat),  the  price  of  one  pound  of  butter  fat  will  be  66-^-4=16% 
cents,  and  the  amount  due  each  patron  is  found  by  multiplying 
the  total  weight  of  butter  fat  *fn  his  milk  by  this  price.  To 
facilitate  this  calculation,  so-called  Relative-Value  Tables  have 
been  constructed,  the  use  of  which  is  explained  below  (238). 

233.  Third. — If  a  creamery-  agrees  to  pay  for  butter  fat,  say 
iy2  cents  per  pound  below  tl*e  average  market  price  of  butter 
each  month,  the  price  of  one"  pound  of  butter  fat  is  found  by 
averaging  the  market  quotations  and  subtracting  1%  cents  there- 
from. If  the  four  weekly  market  prices  were  17%,  17,  16%  and 
19  cents,  the  average  of  these  would  be  17%  cents,  and  this  less 
1%  gives  16  cents  as  the  price  per  pound  of  fat  to  be  paid  to 
the  patrons;  this  price  is  then  used  in  calculating  the  dividend 
as  in  case  of  first  method  (231). 


Patron 

Total 
milk 
tt>s. 

Average 
te*st, 
percent. 

Butter  fat 
tt>s. 

Price  of  fat, 
pr.  lb.,  cents 

Amount 
due 

No.  1... 

13,550 

3.55 

481.0 

16 

$76.96 

No.  2... 
No.  3  

2,825 
7,830 

3.7 

3.9 

104.5 
305.4 

16 
16 

16.72 

48.86 

234.  II.  If  the  creamery  is  owned  by  the  farmers,  the  run- 
ning expenses  for  a  month  are  subtracted  from  the  gross  returns 
received  for  the  butter,  and  the  price  to  be  paid  per  pound  of 
butter  fat  is  found  by  dividing  the  amount  left  by  the  total 
number  of  pounds  of  butter  fat  delivered  during  the  month. 
This  price  is  used  for  paying  e.ach  patron  for  his  milk  according 
to  the  amount  of  fat  contained  therein,  as  already  explained  un- 
der Proprietary  Creameries  (231). 

The  monthly  running  expenses  of  a  co-operative  creamery  gen- 
erally include  such  items  as  the  wages  of  the  butter  maker  (and 
manager  or  secretary,  if  these  officers  are  salaried),  labor  (haul- 
ing, helper,  etc.),  cost  of  butter  packages,  coal  or  wood,  salt 
and  other  supplies,  freight  and  commission  on  the  butter  sold, 
repairs  and  insurance  on  buildings,  etc.  A  certain  amount  is 
also  paid  into  a  sinking  fund  (say,  5  cents  per  100  Ibs.  of  milk), 


Calculating  Dividends.  207 

which  represents  the  depreciation  of  the  property,  wear  and  tear 
of  building  and  machinery,  bad  debts,  etc.  These  items  are 
added  together,  and  their  sum  subtracted  from  the  gross  receipts 
for  the  butter  sold  during  the  month. 

235.  Assuming  the  receipts  for  the  butter  during  the  month 
to  be  $1197,  and  the  running  expenses  of  the  factory  $285,  the 
amount  to  be  divided  among  the  patrons  is  $912;  the  quantity 
of  butter  fat  received  was  5700  Ibs.,  and  the  price  per  pound  of 
butter  fat  will  therefore  be  16  cents.  The  account  will  then 
stand  as  given  in  (233). 

236.  Other  systems  of  payment.    Besides  these  four 
systems  of  payment,  there  are  various  other  agreements 
made   between   manufacturer   and   producer,   but  with 
them  all  the  one  important  computation  is  the  price  to 
be  paid  per  pound  of  butter  fat ;  this  forms  the  b^sis  of 
calculating  the  factory  dividends,  when  milk  is  p.  .d  for 
by  the  Babcock  test. 

237.  Paying  for  butter  delivered.    In  some  instances 
patrons  desire  to  receive  pay  for  the  quantity  of  butter 
which  the  milk  delivered  by  them  will  make.    This  can 
be  ascertained  quite  accurately  from  the  total  receipts 
and  the  total  weights  of  both  butter  fat  and  butter.  The 
total  money  to  be  paid  for  butter  (the  net  receipts)  are 
divided  by  the  number  of  pounds  of  butter  sold,  to  get 
the  price  to  be  paid  per  pound  of  butter;  the  total  yield 
of  butter  divided  by  the  total  amount  of  butter  fat  de- 
livered in  the  milk,  gives  the  amount  of  butter  corre- 
sponding to  one  pound  of  butter  fat,  and  the  number  of 
pounds  of  fat  delivered  by  each  patron  is  then  multi- 
plied by  this  figure.     This  method  requires  more  figur- 
ing than  those  given  in  the  preceding,  and  the  dividends 
are  no  more  accurate,  in  fact  less  so,  than  when  calcula- 
tions are  based  on  the  price  per  pound  of  fat. 


208  Testing  Milk  and  Its  Products. 

238.  Relative-value  tables.  These  tables  give  many 
of  the  multiplications  used  in  computing  the  amount 
due  for  various  weights  of  milk  testing  from  3  to  6  per 
cent,  of  fat.  They  can  easily  be  constructed  by  any  one 
as  soon  as  the  price  of  one  pound  of  fat  is  determined 
in  each  case.  If  the  price  to  be  paid  per  pound  of  fat 
is,  say  15  cents,  the  value  of  each  100  Ibs.  of  milk  of 
different  quality  is  found  by  multiplying  its  test  by  15. 
If  the  average  tests  of  the  different  patrons'  milk  vary 
from  3  to  5  per  cent.,  the  relative-value  table  would  be 
as  follows. 


3.0X15=45c.    per  100  Ibs. 

3.lXl5=46.5c. 

3.2Xl5=48c. 

3.3X15r=49.5c. 

3.4X15=51c. 

3.5X15=52.5c. 


3.6Xl5=54c.    per  100  Ibs. 
3.7Xl5=55.5c.         " 
3.8Xl5=57c.  " 

3.9Xl5=58.5c.         " 
4.0Xl5=60c.  " 

etc. 


By  continuing  this*  multiplication,  or  adding  the  mul- 
tiplier each  time  for  each  tenth  of  a  per  cent,  up  to  5 
per  cent,  of  fat,  a  table  is  made  that  can  be  used  for 
calculating  the  amount  due  per  100  Ibs.  of  milk,  at  this 
price  per  pound,  and  the  weight  of  milk  delivered  by 
each  patron  is  multiplied  by  the  price  per  100  Ibs.  of 
milk  shown  in  the  table  opposite  the  figure  representing 
his  test. 

Example:  A  patron  supplies  2470  Ibs.  of  milk,  testing  3.2 
per  cent,  of  fat;  price  per  pound  of  fat,  15  cents;  he  should 
then  receive  24.70X.48=$11.85  (see  above  table).  Another  pat- 
ron delivering  3850  Ibs.  of  milk  testing  3.8  per  cent,  will  re- 
ceive, at  the  same  price  per  pound  of  fat,  38.50X.57=$21.94. 

The  relative-value  tables  in  the  Appendix  give  the 
price  per  100  Ibs.  of  milk  testing  between  3  and  6  per 
cent,  fat,  when  the  price  of  three  per  cent,  milk  varies 
from  30  to  90c.  per  100  Ibs.  In  using  the  tables,  first 


Calculating  Dividends. 


209 


find  the  figure  showing  the  price  which  it  has  been  de- 
termined to  pay  for  100  Ibs.  of  milk  of  a  certain  qual- 
ity, say  3  or  4  per  cent.-milk;  the  figures  in  the  same 
vertical  column  then  give  the  price  to  be  paid  per  100 
Ibs.  of  milk  testing  between  3  and  6  per  cent. 

Example  1:  It  has  been  decided  to  pay  90  cents  per  100  Ibs. 
of  4  per  cent.-milk.  The  figure  90  is  then  sought  in  the  table  in 
the  same  line  as  4.0  per  cent.,  and  the  vertical  column  in  which 
it  is  found  gives  the  price  per  100  Ibs.  of  3  to  6  per  cent.-milk, 
3.8  per  cent.-milk  is  thus  worth  85  cents  per  100  Ibs.  and  4.5  per 
cent.-milk,  $1.01,  under  the  conditions  given.  The  prices  of  milk 
of  other  qualities  are  found  in  the  same  way. 

Example  2:  In  the  example  referred  to  under  Illustrations  of 
calculating  creamery  dividends  (I  b,  231),  the  figures  for  the 
patrons  Nos.  1,  2  and  3,  would  be  as  follows: 


Patron 

Milk  delivered, 
Ibs. 

Average 
test, 
per  cent. 

Price  per  100  Ibs. 
of  milk,  cents 

Amount 
due 

No.  1 

13,550 

3  55 

58  5 

$79.26 

No.  2  
No.  3 

2,825 
7,830 

3.7 
3  9 

61.0 
64  0 

17.23 
50  XI 

239.  Milk-  and  cream  dividends^  When  cream  from 
farm  hand  separators  or  ether  sources  is  brought  to  a 
factory  receiving  and  skimming  whole  milk,  the  cream 
patron's  dividend  should  be  calculated  a  little  differ- 
ently than  that  of  the  milk  patron. 

In  one  case  the  dividend  is  based  on  the  weight  and 
the  test  of  cream  and  in  the  other  on  the  weight  and 
the  test  of  milk;  the  difference  between  the  two  being 
represented  by  the  fat  left  in  the  factory  skim  milk. 
This  skim  milk  fat  is  included  in  the  milk  patron's 
dividend  and  consequently  ought  also  to  be  allowed  for 
in  calculating  the  amount  due  the  cream  patron.  Such 


14 


210  Testing  Milk  and  Its  Products. 

an  allowance  can  be  fairly  made  by  multiplying  the 
cream  fat  by  1.03.  This  is  assuming  that  the  one-tenth 
or  more  of  fat  returned  to  the  milk  patron  in  his  skim 
milk  is  about  three  per  cent,  of  the  total  fat  in  his  whole 
milk. 

Both  milk  and  cream  patron  suffer  the  same  manu- 
facturing losses  in  the  butter  milk  so  that  an  equaliza- 
tion of  the  skimming  losses  is  all  that  is  necessary  in 
order  to  put  both  on  a  uniform  basis  for  calculating 
dividends. 

240.  The  following  illustration  will  help  to  make  these  cal- 
culations clearer.  Milk  patron  No.  1  delivers  to  the  creamery 
during  the  month  5320  Ibs.  of  milk  testing  3.8  per  cent,  fat, 
which  therefore  contains  (^*f>8)  =202  Ibs.  butter  fat.  If  the 
price  paid  the  patrons  is  20c.,  then  the  202  lbs.X20c.  amounts  to 
$40.40,  the  money  due  this  patron  for  his  milk.  If  another  pat- 
ron sent  485  Ibs.  of  cream  testing  22.0  per  cent,  fat  to  the  same 
factory  during  the  month,  the  weight  of  fat  in  the  cream  is  first 
found  in  the  same  way  as  in  the  milk.  ^85X2A  =106.7  Ibs.  but- 
ter fat.  Now,  instead  of  multiplying  this  butter  fat  by  20c.,  as 
was  done  for  the  whole  milk  patron,  it  must  first  be  multiplied 
by  1.03,  which  makes  the  necessary  allowance  for  the  skim  milk 
fat  that  the  milk  patron  was  paid  for.  106.7X1.03=109.9  Ibs. 
butter  fat  which  is  now  multiplied  by  20c.  per  pound,  giving 
$21.98.  This  is  the  amount  due  the  cream  patron  when  both 
milk  and  cream  are  received  at  the  same  factory  and  the  cream 
from  both  patrons  is  churned  together.1 

B.— CALCULATING  DIVIDENDS  AT  CHEESE  FACTORIES. 

241.  The  amount  of  cheese  made  from  a  certain  quan- 
tity of  milk  depends,  as  before  shown,  in  a  large  meas- 
ure on  the  richness  of  the  milk  in  butter  fat  (223). 
Rich  milk  will  give  more  cheese  per  hundred  weight 

1  17th  report  Wis.  exp.  station,  p.  90;  20th  report,  pp.  l;JO-l:U. 


Calculating  Dividends.  211 

than  poor  milk,  and  within  the  ordinary  limits  of  nor- 
mal factory  milk  the  increased  yields  will  be  nearly,  but 
not  entirely,  proportional  to  the  fat  contents  of  the  dif- 
ferent kinds  of  milk.  Since  the  quality  of  the  cheese 
produced  from  rich  milk  is  better  than  that  of  cheese 
made  from  thin  milk  and  will  demand  a  higher  price, 
it  follows  that  no  injustice  is  done  by  rating  the  value 
of  milk  for  cheese  production  by  its  fat  content.  This 
subject  was  discussed  frequently  during  the  nineties  in 
experiment  station  publications  and  in  the  dairy  press 
(223).  Among  others,  Babcock  has  shown  that  the  price 
of  cheese  stands  in  a  direct  relation  to  its  fat  content.1 
Prof.  Eobertson,  ex-Commissioner  of  Agriculture  of  Can- 
ada, is  authority  for  the  statement  that  the  quality  of 
the  cheese  made  from  milk  containing  3.0  to  4.0  per 
cent,  of  fat  was  increased  in  value  by  one-eighth  of  a 
cent  per  pound  for  every  two-tenths  of  a  per  cent,  of 
fat  in  the  milk,2  a  figure  which  is  fully  corroborated  by 
Dr.  Babcock 's  results.  The  injustice  of  the  "pooling 
system/7  by  which  all  kinds  of  milk  receive  the  same 
price,  is  evident  from  the  preceding;  if  the  milk  of  a 
certain  patron  is  richer  than  that  of  others,  it  will  make 
a  higher  grade  of  cheese,  and  more  of  it  per  hundred- 
weight; hence  a  higher  price  should  be  paid  for  it. 

Payment  on  the  basis  of  the  fat  content  of  milk  is, 
therefore,  the  most  equitable  method  of  valuing  milk 
for  cheese  making,  and  in  case  of  patrons  of  cheese  fac- 
tories as  with  creamery  patrons,  dividends  should  be 
calculated  on  the  basis  of  the  results  obtained  by  test- 

1  Wisconsin  exp.  station,  llth  report,  p.  134. 

2  Hoard's  Dairyman,  March  29,  1895. 


212  Testing  Milk  and  Its  Products. 

ing  the  milk  delivered.1  The  testing  may  be  conven- 
iently arranged  by  the  method  of  composite  sampling, 
in  the  way  already  described  for  creameries  (180). 

242.  Calculation  of  dividends.  As  with  creameries, 
the  price  to  be  paid  per  pound  of  butter  fat  must  first 
be  ascertained.  The  factory  records  should  show  the 
number  of  pounds  of  cheese  made  from  the  total  milk 
delivered  to  the  factory  during  a  certain  time,  generally 
one  month,  and  the  money  received  for  this  cheese.  The 
cost  of  making  the  cheese  and  all  other  expenses  that 
should  be  paid  for  out  of  the  money  received  for  the 
cheese,  are  deducted  from  the  total  receipts,  and  the 
difference  is  divided  among  the  patrons  in  proportion 
to  the  amounts  of  butter  fat  delivered  in  the  milk. 

The  weights  of  the  milk  delivered  and  the  tests  of  the 
composite  samples  furnish  data  for  calculating  the 
quantities  of  butter  fat  to  be  credited  to  each  patron. 
The  money  to  be  paid  to  the  patrons  is  then  divided  by 
the  total  weight  of  butter  fat  delivered  to  the  factory 
and  the  price  of  one  pound  of  fat  thus  obtained.  The 
money  due  each  patron  is  now  found  by  multiplying 
the  total  number  of  pounds  of  butter  fat  in  his  milk  by 
this  price  per  pound. 

The  illustrations  already  given  for  calculating  patrons' 
dividends  at  creameries  according  to  the  various  meth- 
ods will  serve  equally  well  to  show  the  manner  in  which 

1  Prof.  Dean  of  Quelph  (Ont.)  agricultural  college  advocates  adding 
2  to  the  per  cent  fat  in  the  milk  in  calculating  the  money  due  patrons 
for  milk  delivered- at  cheese  factories.  This  method  has  IMM-II  adopted 
at  many  Canadian  cheese  factories  and  also  at  some  factories  in  this 
country.  (Bull.  114,  Ont.  agr,  college;  Dean, Canadian  Dairyman,  p,  1N'>.) 


Calculating  Dividends. 


213 


dividends  are  calculated  at  a  cheese  factory.  For  the 
sake  of  clearness  an  example  is  given  that  applies  di- 
rectly to  cheese  factories. 

243.  Illustration  of  calculation  of  dividends.    It  may   be 

assumed  that  15,000  libs,  of  green  cheese  is  made  from  150,000 
Ibs.  of  milk  delivered  to  a  factory  in  a  Inonth.  According  to  the 
weighings  and  the  tests  made,  the  milk  contained  5,700  Ibs.  of 
butter  fat.  If  thei  cheese  sold  at  an  average  price  of  7^  cents 
a  pound,  the  gross  receipts  would  be  $1,125.00.  The  amount  to 
be  deducted  from  the  gross  receipts  will  depend  on  the  agree- 
ment made  between  the  factory  operator  and  the  patrons,  in 
case  of  proprietary  cheese  factories,  or  between  the  shareholders 
and  the  maker,  when  the  factory  is  run  on  the  co  operative  plan. 
As  before  we  shall  consider  these  systems  separately. 

244.  I.    Proprietary  cheese  factories.     The    owner    of    the 
factory  generally  agrees  to  make  the  cheese  for  a  certain  price 
per  pound  and  to  pay  the  patrons  what  is  left  after  deducting 
this  amount.     If  the  price  agreed  on  is  1^  cents  per  pound  of 
green  cheese,  this  would  amount  to   $225  in  the  example  given. 
Subtracting  this  sum  from  the  gross  receipts,  $1,125,  leaves  $900, 
which  is  to  be  paid  the  patrons.     The  total  amount  of  butter  fat 
delivered  by  the  patrons  was  5,700  Ibs.;  hence  the  price  of  one 
pound   of  butter    fat   will   be   900-^5.700=.1577,   or   15.8   cents. 
Taking  the  figures  for  the  three  patrons  already  mentioned  un- 
der Creamery  Dividends,  we  then  have: 


Patron 

Total  milk, 
Ibs. 

Average 
test, 
per  cent. 

Butter  fat, 
Ibs. 

Price  per 
lb.  of  fat, 
cents 

Amount 
due 

No.  1... 
No.  2  
No.  8  

13,550 
2,825 
7,830 

3.55 
3.7 
3.9 

481.0 
104.5 
305.4 

15.8 
15.8 
15.8 

$76.00 
16.51 

48.25 

245.  II.  Co-operative  cheese  factories.  The  method  of  pay- 
ment at  co-operative  cheese  factories  is  nearly  the  same  as  that 
already  given,  except  that  a  certain  sum  representing  the  ex- 
penses is  subtracted  from  the  gross  receipts  for  the  cheese,  and 
the  balance  is  divided  among  the  patrons  according  to  the  amount 


214  Testing  Milk  and  Its  Products. 

of  butter  fat  furnished  by  each,  in  the  same  manner  as  in  the 
above  case,  after  the  price  of  a  pound  of  fat  has  been  obtained. 
The  price  per  100  Ibs.  of  milk  can  be  calculated  in  the  same 
way  as  at  creameries,  by  multiplying  the  test  of  each  lot  by  the 
price  per  pound  of  fat.1 


Questions. 

1.  How  much  money  is  due  each  of  three  patrons  of  a  cream- 
ery when  the  following  weights  of  milk  are  delivered  by  each: 

A —  5750  Ib.  milk,  composite  tests,  4.0 — 4.8 — 4.2  per  cent. 
B —  955  Ib.  milk,  composite  tests,  4.6 — 5.0 — 4.8  per  cent. 
C — 10,538  Ib.  milk,  composite  tests,  3.2—3.5—3.0  per  cent. 

(a)  When  700  Ibs.  of  butter  are  sold  for  $200,  and  the  cost  of 
making  is  3%c.  per  Ib; 

(b)  When  the  factory  agrees  to  pay  $1.00  per  100  Ibs.  milk, 
testing  4%  fat; 

(c)  When  the  operating  expenses  of  the  factory  are  $20  and- 
the  balance  is  paid  the  patrons; 

(d)  When  the  factory  agrees  to  pay  23c.  per  pound  for  butter 
and  to  give  a  14%  overrun? 

2.  How  much  is  due  a  milk  patron  and  a  cream  patron  at  the 
same   factory   when   the  milk   patron    has   delivered    875   Ibs.    of 
milk,  testing  3.9%  fat  and  the  cream  patron  380  Ibs.  cream,  test- 
ing 26%  fat;  the  factory  selling  160  Ibs.  of  butter  at  28c.  per 
Ib.,  and   charging  3c.  per  Ib.  for  making? 

3.  How  much  is  due  patrons  A,  B,  C,  in  question  1,  if  1800 
Ibs.   of  cheese  were  made  and  sold  for  $200.00  and  the  cost  of 
making  the  cheese  is  l^c.  per  Ib.? 

4.  When  cheese  seflls  for  10  cents  per  Ib.,  what  must  the  price 
of  butter  be  to  pay  the  same  price  for  milk,  the  cost  of  making 
being  l1/^  cents  per  Ib.  of  cheese,  and  4  cents  per  Ib.  for  butter? 

1  Suggestions  regarding  the  organization  of  co-operative  cr<  ;nu- 
eries  and  cheese  factories  will  be  found  in  the  Appendix,  following 
Table  XV.  Draft  of  constitution  and  by-laws  for  co-operative  fnrtory 
associations  are  also  given  in  the  Appendix.  It  is  hoped  that  these  will 
prove  helpful  to  farmers  who  contemplate  forming  such  associations. 


CHAPTER  XIV. 

CHEMICAL  ANALYSIS  OF  MILK  AND  ITS 
PRODUCTS. 

246.  An  outline  of  the  methods  followed  in  determin- 
ing quantitatively  the  main  components  of  milk  and  its 
products  is  given  in  the  following  for  the  guidance  of 
more  advanced  dairy  students.     This  work  cannot  be 
done  outside  of  a  fairly  well-equipped  chemical  labora- 
tory, or  by  persons  who  have  not  been  accustomed  to 
handling   delicate   chemical   apparatus   and    glassware, 
analytical  balances,  etc.,  and  who  have  not  a  knowledge 
of,   at  least,  the   elements   of   chemistry   and   chemical 
reactions. 

A.— MILK. 

247.  In  a  complete  milk  analysis,  the  specific  gravity 
of  the  milk  is  determined,  and  the  following  milk  com- 
ponents: water,   fat,   casein  and  albumon,  milk  sugar, 
and  ash.     The  methods  of  analysis  described  in  the  fol- 
lowing are  those  adopted  by  the  Association  of  Official 
Agricultural  Chemists,  which,  with  but  slight  modifica- 
tions, are  in  general  use  in  the  chemical  laboratories  of 
all  American  experiment  stations  and  agricultural  col- 
leges.1 

1  The  complete  methods  of  analysis  adopted  by  the  Association  of 
Official  Agricultural  Chemists  are  published  by  the  Bur.  of  Chemistry 
of  the  U.  8.  Department  of  Agriculture;  see  Bull.  No.  107,  pp.  117-128. 


216  Testing  Milk  and  Its  Products. 

248.  a.  Specific  gravity  is  determined  by  means  of 
a  picnometer  cr  specific-gravity  bottle,  since  more  ac- 
curate results  will  thus  be  reached  than  by  using  an  or- 
dinary Quevenne  lactometer.  A  thermometer  is  ground 
into  the  neck  of  the  specific-gravity  bottle  so  as  to  form 
a  stopper,  and  the  bottle  is  provided  with  a  glass-stop- 
pered side-tube,  to  furnish  an  exit  for  the  liquid  on  ex- 
panding. A  specific-gravity  bottle  holding  100  grams 
of  water  is  preferably  used.  The  empty  and  scrupu- 
lously cleaned  bottle  is  first  weighed  on  a  chemical  bal- 
ance. The  bottle  is  then  filled  with  recently-boiled  dis- 
tilled water  of  a  temperature  below  60°  F.  (15.5°  C.)  ; 
the  thermometer  is  inserted,  and  the  bottle  is  warmed 
slightly  by  immersing  it  for  a  moment  in  tepid  water 
and  left  standing  until  the  thermometer  shows  60°  F. ; 
the  opening  of  the  side  tube  is  then  wiped  off  and  closed 
with  the  stopper,  and  the  water  on  the  outside  of  the 
bottle  and  in  the  groove  between  its  neck  and  the  ther- 
mometer is  wiped  off  with  filter  paper  or  a  clean  hand- 
kerchief, when  the  bottle  is  again  weighed.  The  weight 
being  recorded,  the  bottle  is  emptied  and  dried  in  a 
water  oven,  or  if  sufficient  milk  is  at  hand,  the  bottle  is 
repeatedly  rinsed  with  the  milk,  the  specific  gravity  of 
which  is  to  be  determined.  It  is  then  filled  with  milk 
in  a  vsimilar  manner  as  in  case  of  water ;  the  tempera- 
ture of  the  milk  should  be  slightly  below  60°  F.  and  is 
slowly  brought  up  to  this  degree  after  the  bottle  has 
been  filled,  proceeding  in  the  same  way  as  before  with 
water ;  the  weight  of  the  bottle  and  milk  is  then  taken. 

The  weights  of  water  and  of  milk  contained  in  the 
specific-gravity  bottle  are  found  by  subtracting  the 


Chemical  Analysis  of  Milk  and  Its  Products.    217 

weight  of  the  empty  bottle  from  the  second  and  the 
third  weights,  respectively,  and  the  specific  gravity  of 
the  milk  then  found  by  dividing  the  weight  of  the  milk 
by  that  of  the  water. 

Example:     Weight  of  sp.  gr.  bottle-f-water . .  .146.9113  grams. 
Weight  of  sp.   gr.  bottle  empty.  .  .   46.9423  grams. 

Weight    of    water 99.9690  grams. 

Weight  of   sp.   gr.  bottle+milk 149.8708  grams. 

Weight  of  sp.   gr.  bottle  empty.  .  .   46.9423  grams. 

Weight  of  milk 102.9285  grams. 

Sp.  gr.  of  milk=:1-|^r=1.0296 

249.  If  a  plain  picnometer  without  a  thermometer  attached, 
is  available,  the  method  of  procedure  is  similar  to  that  described, 
with  the  difference  that  the  temperature  of  the  water  and  of  the 
milk  must  be  brought  to  60°  F.  before  the  picnometer  is  filled, 
or  the  picnometer  filled  with  either  liquid  is  placed  in  water  in  a 
small  beaker,  which  is  very  slowly  warmed  to  60°  F.  and  kept  at 
this  temperature  for  some  time  so  as  to  allow  the  liquid  in  the 
picnometer  to  reach  the  temperature  desired;  the  temperature  of 
the  water  in  the  beaker  is  ascertained  by  means  of  an  accurate 
chemical  thermometer.  The  perforated  stopper  is  then  wiped  off, 
the  picnometer  is  taken  out  of  the  water,  wiped  and  weighed.  It 
is  necessary  to  weigh  very  quickly  if  the  room  temperature  is 
much  above  60°  F..  as  in  such  cases  the  expanding  liquid  will 
flow  on  to  the  balance  pan,  with  a  resultant  loss  in  weight  from 
evaporation. 

The  weights  of  specific-gravity  bottle  or  picnometer,  empty 
and  filled  with  water,  need  only  be  determined  a  couple  of  times, 
and  the  averages  of  these  weighings  are  used  in  subsequent  de- 
terminations. 

250.  Westphal  balance.  Where  only  a  small^  amount 
of  milk  is  available,  or  in  rapid  work,  the  specific  grav- 
ity may  be  taken  with  considerable  accuracy  by  means 
of  a  Westphal  balance.  The  arrangement  and  use  of 
this  convenient  little  apparatus  is  readily  explained 
verbally. 


218  Testing  Milk  and  Its  Products. 

For  the  determination  of  the  specific  gravity  of  lop- 
pered  milk,  see  263. 

251.  b.  Water.  The  milk  is  weighed  into  a  perfor- 
ated copper  tube  filled  with  prepared  dry  asbestos.  The 
tubes  are  made  from  perforated  sheet  copper,  with  holes 
about  .7  mm.  in  diameter  and  about  .7  mm.  apart ;  they 
are  60  mm.  long,  20  mm.  in  diameter  and  closed  at  the 
bottom.  The  asbestos  is  prepared  from  clean  fibrous 
asbestos,  which  is  ignited  at  low  heat  in  a  muffle  oven, 
treated  with  a  little  dilute  HC1  (1:3)  and  then  with 
distilled  water  till  all  acid  is  washed  out;  it  is  then 
torn  in  loose  layers  and  dried  at  a  low  temperature  in 
an  air  bath ;  when  dry  it  can  be  easily  shredded  in  fine 
strings  and  is  placed  in  a  wide-mouth,  glass-stoppered 
bottle. 

About  two  grams  of  asbestos  are  placed  in  each  tube, 
packing  it  rather  loosely;  the  tube  is  then  weighed,  a 
small  narrow  beaker  being  inverted  over  it  on  the  scale 
pan.  5  cc.  of  milk  are  now  dropped  on  to  the  asbestos 
from  a  5  cc.  fixed  pipette,  the  beaker  again  placed  over 
the  tube,  and  the  weight  of  the  5  cc.  of  milk  delivered 
+copper  tube  taken.  The  weight  of  the  milk  is  ob- 
tained by  difference.  The  tubes  are  then  placed  in  a 
steam  oven  and  heated  at  100°  C.  until  they  no  longer 
decrease  in  weight,  which  ordinarily  will  take  about 
three  hours.  Place  in  a  desiccator  until  cold,  and  weigh ; 
the  difference  between  the  weight  of  the  tube-fmilk  and 
this  last  weight  gives  the  water  contained  in  the  milk, 
which  is  then  calculated  in  per  cent,  of  the  quantity  of 
milk  weighed  out. 


Chemical  Analysis  of  Milk  and  Its  Products.    219 

Example:      Weight    of    tube-fbeaker+milk  ----   29.3004  grams. 
Weight  of   tube-fbeaker  ..........   24.1772  grams. 

Milk    weighed    out  ..........     5.1232  grams. 

Weight   of    tube+beaker+milk  ____   29.3004  grams. 

Weight    of    tube+beaker+milk,dry  24.9257  grams. 

Weight    of    water  ...........     4.3747  grams. 


Per  cent,  of  water  in  milk—  —  85.39  per  cent. 

O.  12t)jS 

Note.  The  per  cent,  of  total  solids  in  milk  is  often 
given,  instead  of  that  of  water;  this  may  be  readily  ob- 
tained by  subtracting  the  weight  of  the  empty  tube 
from  that  of  the  tube  filled  with  milk  solids,  and  finding 
the  per  cent,  of  the  milk  weighed  out  which  this  differ- 
ence makes.  In  the  above  example,  the  weight  of  milk 
solids  thus  is  24.9257—  24:1772=7485  gram,  and  the 
per  cent,  of  total  solids  in  the  milk=14.61  per  cent. 

252.  Alternate  Method.  Five  cc.  of  milk  are  measured  out 
on  a  weighed  flat  porcelain  dish  (50-60  mm.  in  diameter;  porce- 
lain crucible  covers  will  answer  the  purpose  better  than  any 
other  vessel  on  the  market,  if  the  handles  be  broken  off  or  ground 
off  level  on  an  emery  wheel)  ;  this  is  weighed  rapidly;  two  or 
three  drops  of  30  per  cent.-acetic  acid  are  added,  and  the  dish 
is  dried  in  a  steam  oven  at  100°  C.  until  no  further  loss  in 
weight  is  obtained.  After  cooling  in  a  desiccator,  the  weight  of 
the  milk  solids  is  obtained,  and  by  calculation  as  before,  the  per 
cent,  of  water  or  total  solids  in  the  milk. 

253.  c.  Fat.  The  dried  tubes  from  the  water  deter- 
mination are  placed  in  Caldwell  extractors  and  con- 
nected with  weighed,  numbered  glass  flasks  (capacity, 
2-3  oz.)  ;  the  extractors  are  attached  to  upright  Liebig 
condensers  and  the  tubes  extracted  with  pure  ether, 
free  from  water,  alcohol  or  acid,  until  all  fat  is  dis- 
solved; 4-5  hours'  extraction  is  sufficient  for  whole 
milk  ;  in  case  of  samples  of  skim  milk  it  is  well  to  con- 
tinue the  extraction  for  8  hours.  The  ether  is  then  dis- 


220  Testing  Milk  and  Its  Products. 

tilled  off  -and  recovered,  and  the  flasks  dried  in  a  cop- 
per oven  until  constant  weight;  after  cooling  they  are 
weighed  and  the  amount  of  fat  contained  in  the  quan- 
tity of  milk  originally  weighed  into  the  tubes  is  thus 
ascertained,  and  the  per  cent,  present  in  the  milk  cal- 
culated. 

Example:     Weight   of    flask  +  f  at  .............  15.8039  grams. 

Weight    of    flask  .................  15.5171  grams. 

Weight  of  fat  ...............  2868  gram. 

Milk    weighed    out  .............................     5.1232  grams. 


Per  cent,  of  fat  in  milk==5.60  per  cent. 

5.  12oz 

254.  The  Gottlieb  method  for  the  determination 
of  fat.1  10  cc.  of  milk  are  measured  into  a  glass  cyl- 
inder, %  inch  in  diameter  and  about  14  inches  long  (a 
100  cc.  burette  or  a  Eudiometer  tube  will  do)  ;  1  cc. 
cone,  ammonia  is  added  and  mixed  thoroughly  with  the 
milk;  the  following  chemicals  are  next  added  in  the 
order  given:  10  cc.  of  92  per  cent,  afcohol,  25  cc.  of 
washed  ether,  and  25  cc.  petroleum  ether  (boiling  pt., 
below  80°  C.),  the  cylinder  being  closed  with  a  moist- 
ened cork  stopper  and  the  contents  shaken  several  times 
after  the  addition  of  each.  The  cylinder  is  then  left 
standing  for  six  hours  or  more.  The  clear  fat  solution 
is  next  pipetted  off  into  a  small  weighed  flask,  by  means 
of  a  siphon  drawn  to  a  fine  point  (see  fig.  6,  loc.  cit.), 
which  is  lowered  into  the  fat  solution  to  within  1/2  cm- 
of  the  turbid  bottom  layer.  After  evaporating  the  ether 
solution  in  a  hood,  the  flasks  are  dried  in  a  steam  oven 
for  two  to  three  hours,  and  weighed.  This  method  is 
applicable  to  new  milk,  skim  milk,  butter  milk,  whey, 

1  Landw.  Vers.  Sta.,  40  (1892),  pp.  1-27.  The  method  is  also  spoken  of 
as  the  Rose-Gottlieb  method. 


Chemical  Analysis  of  Milk  and  Its  Products.    221 

cream,  cheese,  condensed  milk  and  milk  powder,  but  has 
been  found  of  special  value  for  determining  fat  in  skim 
milk,  butter  milk,  cheese,  and  condensed  milk.  In  the 
case  of  products  high  in  fat,  a  second  treatment  with 
10  cc.  each  of  ether  and  petroleum  is  advisable  in  order 
to  recover  the  last  traces  of  fat. 

255.  d.  Casein  and  albumen.  The  sum  of  these  com- 
ponents is  generally  determined  by  the  Kjeldahl 
method.1  5  cc.  of  milk  are  measured  carefully  into  a 
flat-bottom  800  cc.  Jena  flask,  20  cc.  of  concentrated  sul- 
furic  acid  (C.  P. ;  sp.  gr.,  1.84)  are  added,  and  .7  gram 
of  mercuric  oxid  (or  its  equivalent  in  metallic  mer- 
cury) ;  the  mixture  is  then  heated  over  direct  flame 
until  it  is  straw-colored  or  perfectly  white;  a  few  crys- 
tals of  potassium  permanganate  are  now  added  till  the 
color  of  the  liquid  remains  green.  All  the  nitrogen  in 
the  milk  has  then  been  converted  into  the  form  of  am- 
monium sulfate.  After  cooling,  200  cc.  of  ammonia- 
free  distilled  water  are  added,  20  cc.  of  a  solution  of 
potassium  sulfid  (containing  40  grams  sulfid  per  liter), 
and  a  fraction  of  a  gram  of  powdered  zinc.  A  quan- 
tity of  semi-normal  HCl-solution,  more  than  sufficient 
to  neutralize  the  ammonia  obtained  in  the  oxidation  of 
the  milk,  is  now  carefully  measured  out  from  a  delicate 
burette  (divided  into  -fa  cc.)  into  an  Erlenmeyer  flask, 
and  the  flask  connected  with  a  distillation  apparatus. 
At  the  other  end,  the  Jena  flask  containing  the  watery 
solution  of  the  ammonium  sulfate  is  connected,  after 
adding  50  cc.  of  a  concentrated  soda  solution  (1  pound 
"pure  potash"  dissolved  in  500  cc.  of  distilled  water 

1  Fresenius'  Zeitschrift,  22,  p.  366;  U.  S.  Dept.  Agr.,  Bur.  of  Ohem., 
Bull.  107,  p.  5. 


222  Testing  Milk  and  Its  Products. 

and  allowed  to  settle)  ;  the  contents  of  the  Jena  flasks 
are  now  heated  to  boiling,  and  the  distillation  is  contin- 
ued for  forty  minutes  to  an  hour,  until  all  ammonia 
has  been  distilled  over. 

The  excess  of  acid  in  the  Erlenmeyer  receiving-flask 
is  then  accurately  titrated  back  by  means  of  a  tenth- 
normal  standard  ammonia-solution,  using  a  cochineal- 
solution1  as  an  indicator.  From  the  amount  of  acid 
used,  the  per  cent,  of  nitrogen  is  obtained;  and  from  it, 
the  per  cent,  of  casein  and  albumen  in  the  milk  by  mul- 
tiplying by  6.25.2  The  amount  of  nitrogen  contained  in 
the  chemicals  used  is  determined  by  blank  experiments 
and  deducted  from  the  nitrogen  obtained  as  described. 

Example:  The  weight  of  5  cc.  of  milk  (as  obtained  in  deter- 
mining the  water  in  the  milk)  was  5.1465  grams.  5  cc.  of  stand 
ard  HC1  are  added  to  the  receiver,  and  1.55  cc.  of  -  -  alkali- 
solution  are  used  in  titrating  back  the  excess  of  acid.  1.55  cc. 

of   -^-  alkali=^^=.31    cc.  —  acid-solution;    the   ammonia   dis- 

10  5 

tilled    over    therefore    neutralized    5.00 — .31=4.69    cc.    acid.     By 

blank  trials  it  was  found  that  the  reagents  used  furnished  an 
equivalent  of  .02  cc.  acid  in  the  distillate;  this  quantity  sub- 
tracted from  the  acid-equivalent  of  the  nitrogen  of  the  milk 
leaves  4.67  cc.  1  cc.  semi-normal  HCl-solution  corresponds  to 
7  milligrams  or  .007  gram  of  nitrogen;  4.67  cc.  -^-HCl  therefore 
represents  .03269  gram  of  nitrogen.  The  quantity  of  nitrogen 
was  obtained  from  the  5.1465  grams  of  milk  measured  out;  the 
milk  therefore  contains  i^^^-=.635  per  cent,  of  nitrogen,  and 
.635X6.25=3.97  per  cent,  of  casein  and  albumeto. 

256.  Casein  and  albumen  may  be  determined  sepa- 
rately by  Van  Slyke's  method;3  10  grams  of  milk  are 

1  Sutton,  Volumetric  Analysis,  4th  edition,  p.  ttl. 

2  The  factor  6.30  or  6.37  is  more  correct  for  the  albuminoids  of  milk, 
but  has  not  yet  been  generally  adopted  (p.  15,  foot  note>. 

8  Bulletin  107,  p.  117,  Bur.  of  Ohem.,  U.  S.  Dept.  of  Agriculture. 


Chemical  Analysis  of  Milk  and  Its  Products.    223 

weighed  out  and  diluted  with  about  90  cc.  of  water  at 
40°-42°  C.  1.5  cc.  of  a  10  per  cent,  acetic-acid  solution 
are  then  added ;  the  mixture  is  well  stirred  with  a  glass 
rod  and  the  precipitate  allowed  to  settle  for  3-5  min- 
utes. The  whey  is  decanted  through  a  filter  and  the 
precipitate  washed  two  or  three  times  with  cold  water. 
The  nitrogen  is  determined  in  the  filter  paper  and  its 
contents  by  the  Kjeldahl  method;  blank  determinations 
with  the  regular  quantities  of  chemicals  and  the  filter 
paper  used  are  made,  and  the  nitrogen  found  therein 
deducted.  The  per  cent,  of  nitrogen  obtained  multi- 
plied by  6.25  gives  the  per  cent,  of  casein  in  the  milk. 

257.  Albumen  is  determined  in  the  filtrate  from  the 
casein-precipitate ;  the  filtrate  is  placed  on  a  water  bath 
and  heated  to  boiling  temperature  of  water  for  ten  to 
fifteen  minutes.     The  washed  precipitate  is  then  treated 
by  the  Kjeldahl  method  for  the  determination  of  nitro- 
gen; the  amount  of  nitrogen  multiplied  by  6.25  gives 
the  amount  of  albumen  in  the  milk.     The  difference  be- 
tween the  total  nitrogenous  components  found  by  the 
Kjeldahl  method,   arid  the  sum  of  the  casein  and  the 
albumen,  as  given  above,  is  due  to  the  presence  in  milk 
of  a  third  class  of  nitrogen  compounds   (18). 

258.  Hart's  test  for  casein  in  milk.     The  folllowing 
test  for  casein  in  milk  has  been  published  by  the  Wis- 
consin experiment  station  r1 

Two  cc.  of  chloroform,  20  cc.  of  a  .25  per  cent,  solu- 
tion of  acetic  acid,  and  5  cc.  of  milk  (both  these  latter 
of  a  temperature  of  about  70°  F.)  are  measured  into 
small  tubes  of  special  construction  holding  about  35  cc., 

1  Report  24,  p.  117:  "A  simple  method  for  the  estimation  of  casein 
in  cow's  milk,"  by  E.  B.  Hart. 


224  Testing  Milk  and  Its  Products. 

the  lower  end  of  which  is  narrow  and  graduated  to 
.1  cc.  The  mixture  is  shaken  for  10  to  20  minutes  and 
the  tubes  then  whirled  7y2  or  8  minutes  in  a  centri- 
fuge of  15  inches  diameter,  making  2000  revolutions  per 
minute.  (The  use  of  a  metronome  is  recommended  to 
facilitate  the  control  of  the  speed.)  After  whirling, 
the  tubes  are  taken  out  of  the  centrifuge  and  allowed 
to  stand  for  10  minutes,  and  the  percentage  of  casein 
read  off  directly  from  the  scale  on  the  lower  end  of  the 
casein  when  5  cc.  of  milk  are  measured  out.  The  test 
tubes,  each  division  of  which  represents  .2  per  cent,  of 
casein  when  5  cc.  of  milk  are  measured  out.  The  test 
calls  for  considerable  nicety  of  manipulation,  but  ap- 
pears to  give  reliable  results  when  properly  conducted. 

259.  e.  Milk  sugar  is  generally  determined  by  differ- 
ence, the  sum  of  fat,  casein  and  albumen  (totalNX6.25), 
and  ash,  being  subtracted  from  the  total  solids.  It  may 
be  determined  directly  by  means  of  a  polariscope,  or 
gravimetrically  by  Fehling's  solution;  only  the  former 
method,  as  worked  out  by  Wiley,1  will  be  given  here. 

The  specific  gravity  of  the  milk  is  accurately  deter- 
mined, and  the  following  quantities  of  milk  are  meas- 
ured out  -by  means  of  a  100  cc.  pipette  graduated  to  .2 
cc.  (or  a  64  cc.  pipette  made  especially  fcr  this  purpose, 
with  marks  on  the  stem  between  63.7  and  64.3  cc.),  ac- 
cording to  the  specific  gravities  given :  1.026,  64  3  ce. : 
1.028,  64.15  cc.;  1.030,  64.0  cc.;  1.032,  63.9  cc.;  1.034, 
63.8  cc.;  1.036,  63.7  cc.  These  quantities  refer  to  the 
Schmidt-Haensch  half-shadow  polariscopes,  standard- 
ized for  a  normal  weight  of  26.048  grams  of  sugar.  The 
milk  is  measured  into  a  small  flask  graduated  at  100  cc. 

i  Agricultural  Analysis,  ill,  p.  275;  Am.  Ohem.  Jour.,  6,  p.  289  et  seq. 


Chemical  Analysis  of  Milk  and  Its  Products.    225 

and  102.6  cc. ;  30  cc.  of  mercuric-icdid  solution  (pre- 
pared from  33.2  grams  potassium  iodid,  13.5  grams  mer- 
curic chlorid,  20  cc.  glacial  acetic  acid  and  640  cc. 
water)  are  added;  the  flask  is  filled  to  102.6  cc.  mark 
with  distilled  water,  the  contents  mixed,  filtered  through 
a  dry  filter,  and  when  the  filtrate  is  perfectly  clear,  the 
solution  is  polarized  in  a  200  millimeter  tube.  The 
reading  of  the  scale  divided  by  2,  shows  the  per  cent, 
of  lactose  (milk  sugar)  in  the  milk.  Take  five  readings 
of  two  different  portions  of  the  filtrate,  and  average 
the  results. 

260.  f.  Ash.    About  20  cc.  of  milk  are  measured  into 
a  flat-bottom  porcelain  dish  and  weighed ;  about  one-half 
of  a  cc.  of  30  per  cent.-acetic  acid  is  added,  and  the 
milk  first  dried  on  water  bath  and  then  ignited  in  a 
muffle  oven  at  a  low  red  heat.     Direct  heat  should  not 
be  applied  in  •  determining  the  ash  in  milk,  since  alkali 
chlorids  are  likely  to  be  lost  at  the  temperature  to  which 
milk  sclids  have  to  be  heated  to  ignite  all  organic  carbon. 

Example:     Weight  of  porcelain   dish -f  milk 49.0907  grams. 

Weight   of    porcelain   dish 28.3538  grams. 

Weight    of    milk 20.7369  grams. 

Weight  of   dish + milk,  after  ignition  28.5037  grams 
Weight    of    dish 28.3538  grams. 

Weight  of  milk   ash 1499  gram. 

Per  cent,  of  ash^r^^^  — 72  per  cent. 
The  residue  from  the  determination  of  solids   (252) 
may  also  be  used  for  the  ash  determination. 

261.  Acidity  of  milk.    The  acidity  of  milk  is  conven- 
iently  determined   by  means   of  Farrington's   alkaline 
tablets   (see  p.   122),  or  by  a  tenth-normal  soda  solu- 
tion.   In  the  latter  case  20  cc.  of  milk  are  measured  into 

15 


226  Testing  Milk  and  Its  Products. 

a  porcelain  casserole ;  a  few  drops  of  an  alcoholic  phe- 
nolphtalein  solution  are  added,  and  soda  solution  is 
dropped  in  slowly  from  a  burette  until  the  color  of  the 
milk  remains  uniformly  pinkish  on  agitation.  1  cc,  of 
Y^  alkali  corresponds  to  .009  gram  lactic  acid,  or  to 
.045  per  cent,  when  20  cc.  of  milk  are  taken  (see  p.  121). 

B.— CREAM,  SKIM  MILK,  BUTTER  MILK,  WHEY,  CON- 
DENSED MILK. 

262.  The  analysis  of  these  products  is  conducted  in 
the  same  manner  as  in  case  of  whole  milk,  and  the  same 
constituents  are  determined,  when  a  complete  analysis 
is   wanted.     Skim    milk,    butter    milk,    and    whey    con- 
tain   relatively    small    quantities    of   solids,    and    espe- 
cially of  fat,  and  it  is,  therefore,  well  to  weigh  out  a 
larger  quantity  than  in  case  of  whole  milk;  if  possible, 
toward  10  grams.     The  acidity  of  sour  milk  and  butter 
milk  must  be  neutralized  with  sodium  carbonate  pre- 
vious to  the  drying  and  extraction,  as  lactic  acid  is  solu- 
ble in  ether  and  would  thus  tend  to  increase  the  ether- 
extract  (fat),  if  not  combined  with  an  alkali  previous 
to  the  extraction. 

263.  Specific  gravity  of  butter  milk.     The  specific   gravity 
of  butter  milk    (as  well   as  of  sour   or  loppered  milk)    is  deter- 
mined  by    Weibull  's   method ;    a   known    volume    of    the    milk    is 
mixed  with  a  certain  amount   (say  10  per  cent.)   of  ammonia  of 
a  definite  specific  gravity,  and  the  specific  gravity  of   the  liquid 
determined   after  thorough   mixing   and   subsequent   standing   for 
an  hour.     If  A  designate  the  volume  of  butter  milk  taken,  B  that 
of  ammonia,   and   C  that  of  the  mixture;   and  if  furthermore   S 
designate  the  specific  gravity  of  the  butter  milk,  s^  that  of  the 
ammonia,  and  s2  that  of  the  mixture,  we  have 

Cs2— Bs, 


Chemical  Analysis  of  Milk  and  Its  Products.    227 

Klein1  has  modified  this  method  by  weighing  the  liquids,  thus 
securing  greater  accuracy  ;  22  to  24  per  cent.-ammonia  is  used, 
one-tenth  as  much  being  taken  as  the  amount  of  milk  weighed 
out.  The  results  come  uniformly  .0005  too  high,  and  this  correc- 
tion should  always  be  made.  The  following  formula  will  give 
the  specific  gravity  of  the  milk,  which  in  case  of  careful  work 
will  be  accurate  to  one-half  lactometer  degree;  if  the  letters 
given  above  designate  weights  (instead  of  volumes  as  before) 
and  specific  gravities  of  the  liquids,  respectively,  we  have 

A 

~    ~~ 


264.  Condensed  milk.  The  same  methods  are,  in  gen- 
eral, followed  in  the  analysis  of  condensed  milk  as  with 
whole  milk.  Condensed  milk  is  preferably  diluted  with 
five  times  its  weight  of  water  prior  to  the  analysis,  both 
because  such  a  solution  can  be  more  easily  handled 
than  the  undiluted  thick  condensed  milk,  and  the  errors 
of  analysis  are  thereby  reduced,  and  because  the  fat  is 
not  readily  extracted  except  when  the  milk  has  been 
diluted.2  The  same  constituents  are  determined  as  in 
case  of  whole  milk,  viz.,  solids,  fat,  casein  and  albumen, 
ash,  milk  sugar,  and  cane  sugar  (if  any  has  been  added 
to  the  milk)  .  The  cane  sugar  is  determined  by  the  dif- 
ference between  the  solids  not  fat  and  the  sum  of  the 
casein,  albumen,  milk  sugar  and  ash  ;  if  the  student  has 
a  knowledge  of  the  manipulation  of  the  polariscope  and 
has  had  experience  in  gravimetric  sugar  analysis,  the 
milk  sugar  is  determined  gravimetrically,  and  the  cane 
sugar  by  the  difference  between  the  polariscope  reading 
after  inversion  and  the  milk  sugar  present. 

1  Milch  z^itunpr,  1896,  p.  656:  see  also  De  Koningh,  Analyst,  1899,  p.  142. 

2  A  second  extractiorf  following  leaching:  and  subsequent  drying  of 
the  tubes  is  necessary  to  extract  all  the  fat  in  condensed  milk:    see 
Bull.  104,  Bur.  of  Ohem.,  IT.  S.  Dept.  of  Agr.,  p.  102  and  154. 


228  Testing  Milk  and  Its  Products. 

The  specific  gravity  of  condensed  milk  may  be  deter- 
mined by  a  method  similar  to  that  of  McGill.1  50  gr. 
of  the  thoroughly  mixed  sample  are  weighed  into  a 
tared  beaker  and  washed  with  warm  water  into  a  250  cc. 
flask,  cooled  to  60°,  filled  to  the  mark  and  carefully 
mixed.  The  specific  gravity  of  this  solution  (a)  is  then 
taken  and  the  original  density  is  calculated  by  means 
of  the  following  formula: 

Sp.  gr.  of  condensed  milk=-l— 

b — 5ft 

Concentration.     The  extent  of  concentration  of  con- 
densed milk  may  be  determined  approximately  by  the 
formula  devised  by  McGill  (loc.  cit.)  : 
Concentration   (c)™-5^ 

fttSi 

where  a  and  £  designate  the  solids  not  fat  and  specific 
gravity,  respectively,  of  the  condensed  milk,  and  a±  and 
s^  the  corresponding  data  for  the  milk  used.  If  $,= 
1.030  and  a±=9  per  cent.,  then  c— -^-  gives  the  con- 
centration. 

C.— BtTTTER. 

265.  Sampling.     A   four-   to    eight-ounce  sample    of 
butter   is   melted    in   a  tightly-closed    pint     fruit   jar, 
shaken  vigorously  and  cooled  until  the  butter  is  hard- 
ened, the  jar  being  shaken  vigorously  at  short  intorva\s 
during  the  cooling  so  as  to  keep  the  water  of  the  butter 
evenly  distributed  in  the  mass. 

266.  a.  Determination    of   water.      Small    pieces    of 
butter  (about  2  grams  in  all)  are  taken  from  the  sam- 
ple by  means  of  a  steel  spatula  and  placed  in  glass  tubes. 
seven-eighths  of  an  inch  in  diameter  and  two  and  a  half 

1  Bulletin  54,  Laboratory  Inland  Rev.  Dept.,  Ottawa,  (1anndn. 


Chemical  Analysis  of  Milk  and  Its  Products.    229 

inches  long,  closed  at  the  bottom  by  a  layer  of  stringy 
asbestos,  and  filled  two-thirds  full  of  asbestos  prepared 
as  for  milk  analysis  (252).  The  tubes  are  dried  at 
100°  C.  in  a  water  oven,  until  no  further  loss  in  weight 
takes  place,  and  are  then  cooled  and  weighed.  The  loss 
in  weight  shows  the  per  cent,  of  water  present. 

267.  b.  Fat.     The  tubes  are  placed  in  Caldwell  ex- 
tractors and  extracted  for  four  hours  with  anhydrous 
ether ;  the  ether  is  then  distilled  off,  and  the  flasks  dried 
in  the  steam  bath  and  weighed,,  the  increase  in  weight 
giving  the  fat  in  the  samples  of  butter  weighed  out. 

268.  c.  Casein.     10  grams  of  butter  are  weighed  into 
a  small  beaker  provided  with  a  lip,  and  treated  twice 
with  about  50  cc.  of  gasoline  each  time;  the  solution  is 
filtered  off,  and  the  residue  transferred  to  a  filter  and 
dried;  its  nitrogen  content  is  then  determined  by  the 
Kjeldahl  method  (255).     The  nitrogen  in  the  filter  and 
the  chemicals  used  is  determined  by  blank  trials  and 
deducted.     The  nitrogen  multiplied  by  6.25   gives  the 
casein  in  the  butter. 

269.  d.  Ash.      (1)    10  grams   of  butter  are  weighed 
into  a  porcelain  dish  and  treated  twice  with  gasoline,  as 
in  the  preceding  determination;  the  solution  is  filtered 
through  an  ash-free  (quantitative)   filter,  and  the  filter 
when  dry  is  transferred  to  the  dish.     The  dish  is  heated 
in  an  air-bath  for  half  an  hour  and  then  placed  in  a 
muffle  oven,  where  the  contents  are  burnt  to  a  light 
grayish  ash;  the  dish  is  now  cooled  in  a  desiccator  and 
weighed.     The  difference  between  this  weight  and  that 
of  the  empty  dish  gives  the  amount  of  ash  in  the  butter 
weighed  out. 


230  Testing  Milk  and  Its  Products. 

270.  (2)    About  two  grams  of  "butter  are  weighed  into 
a  small  porcelain  dish,  half  filled  with  stringy  asbestos ; 
the  dish  is  dried  for  half  an  hour  in  the  water  oven, 
and  the  fat  then  ignited  with  a  match,   the  asbestos 
fibre  serving  as  a  wick.     When  the  flame  has  gone  out, 
the  dish  is  placed  in  a  muffle  oven,  and  the  residue 
burnt    to    a    grayish    ash.    After  cooling,  the  dish  is 
weighed,  and  the  per  cent,  of  ash  in  the  butter  calcu- 
later  as  under  method  1. 

271.  Complete  analysis  of  butter  in  the  same  sam- 
ple.    About  2  grams  of  the  butter  are  weighed  into  a- 
platinum  gooch  half  filled  with  stringy  asbestos,  and 
dried  in  a  water  oven  at  100°  C.  to  constant  weight, 
cooled  and  weighed.     The  difference  gives  water  in  the 
sample.     The    gooch   is   then   treated   repeatedly   with 
small  portions  of  gasoline,  suction  being  applied,  and 
again  dried  in  the  water  oven,  cooled,  and  weighed ;  the 
fat  in  the  sample  is  obtained  from  the  difference  be- 
tween this   and  the   preceding  weight.     The   gooch   is 
then  carefully  heated  over  direct  flame  until  a   light 
grayish   ash  is  obtained;   this   operation  is   preferably 
done  in  a  muffle  oven  to  avoid  a  loss  of  alkali  chlorids. 
The   loss   in  weight    gives    the    casein    in    the    sample 
weighed  out,  and  the  increase  in  the  weight  of  the  gooch 
over  that  of  the  empty  gooch  with  asbestos,  gives  the 
ash  (mainly  salt)   of  the  butter.     The  salt  in  the  ash 
may  be  dissolved  out  by  hot  water,   and  the   chlorin 
content  of  the  solution  determined  by  means  of  a  stand- 
ard silver-nitrate  solution,  using  potassium  chromate  as 
an  indicator. 


Chemical  Analysis  of  Milk  and  Its  Products.    231 

272.  Rapid  estimation  of  water  in  butter.  A  num- 
ber of  different  methods  have  recently  been  proposed 
for  the  rapid  estimation  of  water  in  butter,  the  object 
sought  being  to  enable  the  buttermaker  himself  to  ascer- 
tain the^  water  content  of  his  butter  without  much 
trouble  or  delay,  and  by  using  such  simple  apparatus 
as  he  is  likely  to  have  in  the  creamery  or  can  easily 
procure  at  a  low  price.  The  subject  of  controlling  the 
per  cent,  of  water  in  butter  has  become  more  important 
than  was  earlier  the  case,  through  the  passage  of  the 
pure-food  law  and  the  promulgation  of  government  food 
standards  in  1906  (305)  ;  these  measures  rendered  the 
question  of  guarding  against  an  excessive  water  content 
in  the  butter  one  of  great  importance  to  all  butter- 
makers. 

All  the  methods  suggested  but  three  (Wagner,  Car- 
roll, and  Gray's,  see  below)  are  essentially  the  common 
methods  of  chemical  analysis,  modified  to  meet  the  de- 
mands of  every-day  factory  conditions.  It  is  difficult 
to  predict  which  one  of  these  methods  will  be  generally 
adopted  in  creameries  in  the  future,  but  references  to 
where  descriptions  of  the  different  methods  will  be 
found,  are  given  below,  and  a  few  that  are  most  likely 
to  be  used  in  factories  and  outside  of  chemical  labora- 
tories, are  described  in  detail,  so  that  students  may 
readily  understand  and  employ  any  one  of  these  meth- 
ods that  may  be  deemed  preferable. 

In  all  these  rapid  methods  of  determining  the  water 
content  in  butter,  the  sample  of  butter  must  be  pre- 
pared so  as  to  accurately  represent  the  lot  of  butter 
sampled  and  must  be  carefully  weighed  on  a  delicate 


232  Testing  Milk  and  Its  Products. 

scale,  as  previously  described  (93).  The  directions, 
in  so  far  as  they  are  given  in  detail  in  the  following, 
therefore,  presuppose  that  a  carefully  prepared,  fair 
sample  has  been  obtained  in  all  cases. 

273.  Among  the  methods  recently  proposed  for  the 
rapid  determination  of  the  per  cent,  of  water 
in  butter  that  are  adapted  for  use  in  creamer- 
ies may  be  mentioned : 

Richmond's  method,1  Carroll's  tester,2  Geld- 
ard's  butter  tester,3  the  Irish  "common  sense 
butter  and  cheesy  moisture  test,"  Dean's,4 
Gray's,5  Patrick's,6  and  the  Wisconsin  high- 


pressure  oven  methods.7 


The  followiAg  four  of  these  methods  will  be 
—  "H 
'— ^     briefly  described: 


274.  a.  Gray's  method.  This  ingenious 
method  was  invented  by  Prof.  C.  E.  Gray,  of 
the  Dairy  Division  of  the  U.  S.  Dept.  of  Agri- 
culture, and  was  published  in  1906;  the  method 
consists  of  heating  ten  grams  of  butter  in  a 
special  flask  of  about  70  cc.  capacity  (see  fig. 
^)  with  6  cc.  of  "amyl  reagent"  (five  parts 
°f  amyl  acetate  and  one  part  amyl  valerianate). 
me?hod.s  The  water  is  boiled  out  of  the  butter  by  heating 
over  direct  flame,  and  together  with  some  of  the  reagent, 
is  condensed,  cooled,  and  measured  in  a  graduated  tube 

1  Dairy  Chemistry,  p.  252. 

2  Dept.  of  Agr.,  Ottawa,  Dairy  Tom' r  Branch,  hull.  6,  pp.  10-11. 

3  Dept.  of  Agr.,  Ottawa,  Dai-  y  Oom'r  Branch,  bull.  14,  pp.  6-8. 
«   •*  Ontario  Agr.  College,  rept.  1906,  p.  120. 

«  Oirc.  100,  Bur.  An.  Ind.,  U.  S.  Dept.  of  Agr. 

6  Journal  Am.  Ohem.  Soc.,  28,  1906,  p.  1611. 

7  Bull.  154,  Wis.  cxprnim-nt  station. 


Chemical  Analysis  of  Milk  and  Its  Products.    233 


attached  to  the  flask.  The  accompanying  illustration 
shows  the  arrangement  of  the  distilling  flask  and  the 
graduated  tube  in  which  the  water  is  measured.  For 
details  of  manipulation,  reference  is  made  to  the  orig- 
inal publication,  or  to  the  files  of  our  dairy  press  pub- 
lished during  1906-7.1 

275.  Patrick's  method.  Ten  grams  of  butter  are 
accurately  weighed  into  a  300  cc.  aluminum  beaker 
(about  3  inches  tall  and  2  inches  in  diameter)  ;  this  is 
held  by  means  of  a  hand 
clamp  over  the  flame  of 
the  alcohol  lamp  or  a  gas 
burner  (see  fig.  60)  and 
very  carefuHy  heated  until 
all  the  water  is  expelled. 
The  beaker  is  then  cooled 
by  sinking  it  to  the  rim  in 
water  of  50°  to  60°,  wiped 
dry,  and  the  loss  in  weight 
calculated  as  water.  If  ten 
grams  of  butter  weighed 
8.45  grams  after  heating, 
the  loss  in  weight  of  1.55  grams  represents  15.5  per 
cent,  of  the  weight  of  the  sample,  and  the  butter  there- 
fore contained  15.5  per  cent,  of  water.  The  results  ob- 
tained by  this  method  seldom  vary  more  than  .2  per 
cent,  from  those  of  chemical  analysis,  and*  often  less 
than  .1  per  cent,  when  proper  care  in  sampling  and 
weighing  has  been  taken. 

1  E.  g.,  New  York  Produce  Review,  Jan.  16,  1907;  American  Cheese 
Maker,  Jan.,  1907. 


Fm.  ^  Alumlnum  beaker  and 
ho1  lam>  used  in  the  Patrick 


234  Testing  Milk  and  Its  Products. 

A  few  points  .need  special  attention  in  using  this 
method:  First,  care  must  be  taken  not  to  heat  the 
beaker  too  fast  so  that  spattering  occurs ;  there  is  not  so 
much  danger  from  this  source  when  an  alcohol  lamp  is 
used  as  with  a  gas  burner,  which  easily  raises  the  tem- 
perature too  high,  causing  a  fine  spray  of  material  to 
be  thrown  about,  and  thus  giving  too  high  results  for 
water  content.  Second,  it  is  important  to  discontinue 
the  heating  at  the  exact  point  when  all  the  water  has 
been  driven  oft'  and  before  burning  of  the  non-fatty 
solids  (casein,  milk  sugar,  and  organic  acids)  occurs, 
as  indicated  by  a  slight  darkening  in  color.  It  is  not 
necessary  to  cool  the  beakers  in  water,  but  they  can  be 
left  to  cool  in  the  air.  The  determination  of  water  in 
butter  by  this  method  can  be  finished  in  ten  minutes 
or  less  by  an  experienced  operator.  The  Irish  test  is 
similar  to  the  method  described  in  the  preceding,  dif- 
fering from  the  same  mainly  in  the  shape  of  the  alumi- 
num dishes  used. 

276.  Dean's  method.  Three  cc.  of  a  melted  sample 
of  butter  are  placed  in  an  ordinary  "patty-pan"  tin 
dish  (about  2y2  inches  in  diameter  and  y2  inch  deep) 
and  accurately  weighed;  the  dish  is  then  placed  in  a 
steam  oven  provided  with  a  pop  safety  valve,  a  steam 
pressure  gauge,  and  a  thermometer.  The  oven  used 
by  Professor  Dean,  of  Guelph  (Ont.)  Dairy  School,  the 
originator  of  this  method,  was  6x8  inches.  It  was  made 
of  galvanized  iron  by  a  local  tin-smith  at  a  cost  of 
about  $5.00,  exclusive  of  safety  valve  and  steam  gauge, 
and  was  made  to  withstand  a  pressure  of  about  10 
pounds.  After  five  or  six  hours'  drying  in  the  oven, 


Chemical  Analysis  of  Milk  and  Its  Products.    235 


the  samples  of  butter  are  ready  to  be  weighed,  and  the 
loss  gives  the  amount  of  water  present  therein.  The 
average  results  obtained  by  this  method  with  nine  sam- 
ples of  butter  came  within  .13  per  cent,  of  those  found 
by  chemical  analyses. 

The  same  method  is  recommended  by  the  author  for 
determining  the  per  cent,  of  water  in  curd  or  cheese. 

277.  The  Wisconsin  high-pressure  oven  method 
(see  fig.  61).  Either  10  or  50  grams  of  butter  are 
weighed  in  a  flat-bottomed  tin  or  aluminum  dish.  This 
is  placed  in  an  oven  heated 
by  high-pressure  steam  to  a 
temperature  of  240°  to  280° 
F.  The  length  of  time  re- 
quired to  expel  all  the  water 
from  the  butter  will  depend  on 
the  temperature  of  the  oven 
and  the  diameter  of  the  dish 
in  wThich  the  butter  is  heated. 
If  the  dish  is  large  enough  to 
permit  the  butter  to  spread 
out  into  a  verv  thin  layer  and 

FIG.  61.    The  Wisconsin  high-  - 

the   temperature   of   the    oven  pressure  oven, 

reaches  260°  F.,  the  water  will  be  completely  expelled 
in  half  an  hour.  Ovens  of  this  construction  have  now 
been  placed  on  the  market  by  one  of  the  manufacturers 
of  dairy  supplies.  A  steam  pressure  of  60  Ibs.  and  a 
temperature  of  280°  F.  may  be  obtained  in  such  an 
oven;  by  employing  the  boiler  pressure  ordinarily  used 
in  a  creamery,  temperatures  of  240°  to  260°  may  be 
easily  obtained.  The  temperature  thus  reached  is  suf- 


236  Testing  Milk  and  Its  Products. 

ficiently  high  to  dry  the  cutter  completely  within  an 
hour,  provided  pans  large  enough  to  spread  the  butter 
in  a  thin  layer  are  used. 

If  10  grams  of  butter  are  used  in  making  tests,  a 
more  delicate  scale  is  necessary  than  when  50  grams 
are  taken.  There  are  other  advantages  in  using  as  large 
a  quantity  as  50  grams  of  butter  for  making  tests  of 
water.  First,  a  sample  can  be  taken  directly  from  a 
package  into  a  weighing  pan.  Second,  ordinary  tin 
basins  at  least  5  inches  in  diameter  can  be  used  for  dry- 
ing the  butter.  Third,  scales  with  a  graduated  side 
beam  and  sensitive  to  .1  gram  instead  of  those  with 
smaller  locse  weights  can  be  used  for  weighing  the  but- 
ter. (See  fig.  35.) 

278.  A  practical  method  of  estimating  the  salt  content 
of  butter.  A  method  of  estimating  the  salt  content  of  butter, 
which  is  applicable  also  outside  of  chemical  laboratories,  has 
been  worked  out  jointly  by  Messrs.  Alfred  Vivian  and  C.  L. 
Fitch.1  The  salt  of  the  butter  is  dissolved  in  hot  water,  and  a 
certain  portion  of  the  solution  when  cool  is  pipetted  off  and 
titrated  with  a  silver-nitrate  solution  prepared  by  dissolving  one 
silver-nitrate  tablet  in  50  cc.  water,*  potassium  chromate  being 
used  as  an  indicator.  The  silver  nitrate  tablets  are  sold  for  60 
cents  per  100,  which  number  is  sufficient  to  make  100  to  150  tests. 
The  method  has  been  advertised  in  the  dairy  press  under  the 
name  of  " Fitch's  Salt  Analysis."  Directions  for  making  tests 
by  this  method  are  furnished  with  the  apparatus  when  this  is 
bought.  The  price  of  a  complete  outfit  is  $4.50. 

DETECTION  OF  ARTIFICIAL  BUTTER? 

279.  Determination  of  the  specific  gravity  of  the  fil- 
tered butter  fat  serves  as  a  good  preliminary  test.  A 
number  of  practical  methods  for  the  detection  of  artifi- 
cial butter  have  been  proposed,  but  they  are  either 

1  Wls.  experiment  station,  report  17,  pp.  98-101;  Hoard's  Dairyman, 
February  15, 1901,  "Uniform  Baiting  of  Butter." 


Chemical  Analysis  of  Milk  and  Its  Products.    237 

worthless,  in  case  of  samples  containing  a  considerable 
proportion  of  natural  butter,  or  give  satisfactory  results 
only  in  the  hands  of  experts.  The  Reichert-Wollny 
method  given  in  detail  below  is  the  standard  method  the 
world  over,  and  the  results  obtained  by  it  are  accepted 
in  the  courts. 

280.  Filtering  the  butter  fat.     The  butter  to  be  ex- 
amined is  placed  in  a  small  narrow  beaker  and  kept  at 
60°  C.  for  about  two  hours.     The  clear  supernatant  fat 
is  then  filtered  through  absorbent  cotton  into  a  200  cc. 
Erlenmeyer  flask,  taking  care  that  none  of  the  milky 
lower  portion  of  the  contents  of  the  beaker  be  poured 
on  the  filter.     In  sampling  the  butter  fat,  it  is  poured 
back  and  forth  repeatedly  from  a  small  warm  beaker 
into  the  flask,  and  the  quantity  wanted  is  then  drawn 
off  with  a  warm  pipette. 

281.  Specific  gravity.     This  is  generally  determined 
at  100°  C.     The  method  of  procedure  is  similar  to  that 
described  under  milk  (248).     The  picnometer  (capacity 
about  25  cc.)  is  filled  with  dry  filtered  butter  fat,  free 
from  air  bubbles ;  the  fat  is  heated  for  30  minutes  in  a 
beaker,  the  water  in  which  is  kept  boiling.     On  cooling, 
the  weight  of  picnometer  and  fat  is  obtained,  and  by 
calculation  as  usual,  the  specific  gravity  of  the  fat. 

The  specific  gravity  of  pure  natural  butter  fat  at 
100°  C.  ranges  between  .8650  and  .8685,  while  artificial 
butter  fat  (i.  e.,  fat  from  other  sources  than  cow's  milk) 
has  a  specific  gravity  at  100°  C.  of  below  .8610,  and  gen- 
erally about  .85. 

282.  Reichert-Wollny  method  (Volatile  Acids.}    5.75 
cc.  of  fat  are  measured  into  a  strong  250  cc.  weighed 
saponification  flask,  by  means  of  a  pipette  marked  to 


238  Testing  Milk  and  Its  Products. 

deliver  this  amount,  and  the  flask  when  cool  is  weighed 
again.  20  cc.  of  a  glycerol-soda  solution  (20  cc.  of 
soda  solution  (1:1)  fo  180  cc.  of  pure  glycerol),  are  then 
added  to  the  flask  and  the  flask  is  heated  over  a  naked 
flame  or  hot  asbestos  plate  until  complete  saponification 
has  taken  place,  as  shown  by  the  mixture  becoming  per- 
fectly clear.  If  foaming  occur,  the  flask  is  shaken 
gently. 

135  cc.  of  recently-boiled  distilled  water  are  now 
added,  drop  by  drop,  at  first,  to  prevent  foaming,  and 
when  the  solution  is  clear,  cooled  to  about  70°  C. ;  5  cc. 
of  dilute  sulfuric  acid  (200  cc.  cone.  H2SO4  per  liter)  are 
added  to  the  soap  solution  to  decompose  the  soap  into 
free  fatty  acids  and  glycerol.  A  few  pieces  of  pumice 
stone  (prepared  by  throwing  the  pieces  at  white  heat 
into  distilled  water  and  keeping  them  under  water  until 
used)  are  added,  the  flask  connected  with  a  glass  con- 
denser, heated  slowly  till  boiling  begins,  and  the  con- 
tents then  distilled  at  such  a  rate  as  will  bring  110  cc. 
of  the  distillate  over  in  as  nearly  thirty  minutes  as  pos- 
sible. 

The  distillate  is  mixed  thoroughly  and  filtered 
through  a  dry  filter;  100  cc.  of  the  filtrate  are  poured 
into  a  250  cc.  beaker  and  titrated  with  a  deci-normal 
barium-hydrate  solution,  half  a  cubic  centimeter  of  phe- 
nolphtalein  solution  being  used  as  an  indicator.  A  blank 
test  is  made  in  the  same  manner  as  described,  and  the 
amount  of  alkali  solution  used  deducted  from  the  re- 
sults obtained  with  the  samples  analyzed.  The  number 
of  cubic  centimeters  of  barium-hydrate  solution  used  is 
increased  by  one-tenth,  and  the  so-called  Reichert  or 
Reichert-Meissl  number  thus  obtained. 


Chemical  Analysis 

The  Reichert  number  forv^^4&^^^^^s:ordi- 
narily  come  above  24  cc. ;  butter  faTTrom^stripper  cows 
will  have  a  low  Reichert  number.  Pure  oleomargarine 
will  have  a  Reichert  number  of  1  to  2  cc. ;  and  mixtures 
of  artificial  and  natural  butter  will  give  intermediate 
numbers. 

TESTS  FOB  THE  DETECTION  OF  OLEOMARGARINE  OR  RENO- 
VATED BUTTER. 

283.  The  boiling  test.1    A  piece  of  butter  of  the  size 
of  a  small  chestnut  is  melted  in  an  ordinary  tablespoon 
(or  a  small  tin  dish)  at  a  low  heat,  stirring  with  a  splin- 
ter of  wood.     The  heat  is  increased  until  as  brisk  a  boil 
as  possible,  and  after  boiling  has  begun,  the  melted  mass 
is  stirred  thoroughly  two  or  three  times,  always  shortly 
before    boiling    ceases.     Oleomargarine    and    renovated 
butter  will  boil  noisily,  sputtering  like  a  mixture  of 
grease  and   water  when  boiled,   and  will  produce  but 
little  or  no  foam.    Renovated  butter  produces  usually  a 
very  small  amount  of  foam,  while  genuine  butter  boils 
with  less  noise  and  produces  an  abundance  of  foam. 

284.  The   Waterhouse  test  for   distinguishing  oleo- 
margarine and  renovated  butter.2     Half  fill  a  100  cc. 
beaker  with  sweet  skim  milk  (or  distilled  water),  heat 
nearly  to  boiling  and  add  5  to  10  grams  of  butter  or 
oleomargarine.     Stir  with  a  small  wooden  stick  of  about 
the  size  of  a  match  until  the  fat  is  melted;  the  beaker  is 

1  Patrick,  Household  tests  for  the  detection  of  oleomargarine  and 
renovated  butter,  Farmers'  Bulletin,  No.  131.    For  detection  and  exam- 
ination of  renovated  or  "process"  butter,  see  also    Oochran,    Journ. 
Frankl.  Insf.,  1899,  p.  04;  Analyst,  1899,  p.  88. 

2  Farmers'  Bulletin,  No.  131,  p.  7. 


240  Testing  Milk  and  Its  Products. 

then  placed  in  ice  water,  and  the  milk  (or  water)  stirred 
until  the  temperature  falls  sufficiently  for  the  fat  to 
congeal.  If  oleomargarine,  the  fat  can  now  be  easily 
collected  into  one  lump  by  means  of  the  stick,  while  if 
genuine  or  renovated  butter,  the  fat  will  granulate  and 
can  not  be  so  collected.1 

D.—  CHEESE. 

For  method  of  sampling,  see  p.  104. 

285.  a.  Water.     Five  grams  of  cheese  cut  into  very 
thin  slices  are  weighed  into  a  smdll  porcelain  dish  filled 
about  one-third  full  with  freshly-ignited  stringy  asbes- 
tos ;  the  dish  is  placed  in  a  water  oven  and  heated  for  ten 
hours.     The  loss  in  weight  is  taken  to  represent  water. 
(See  also  Dean's  method  for  determining  water  in  but- 
ter, curd  and  cheese,  p.  234). 

286.  b.  Fat.     About  5  grams  of  cheese  are   ground 
finely  in  a  small  porcelain  mortar  with  about  twice  its 
weight  of  anhydrous  copper  sulf  ate,  until  the  mixture  is 
of  a  uniform  light  blue  color  and  the  cheese  evenly  dis- 
tributed throughout  the  mass.     The  mixture  is  trans- 
ferred to  a  glass  tube  of  the  kind  used  in  butter  analysis 
(263),  only  a  larger  size;  a  little  copper  sulf  ate  is  placed 
at  the  bottom  of  the  tube,  then  the  mixture  containing 
the  cheese,  and  on  top  of  it  a  little  extracted  absorbent 
cotton  or  ignited  stringy  asbestos;  the  tube  is  placed  in 
an  extraction  apparatus  and  extracted  with  anhydrous 
ether  for  fifteen  hours.     The  ether  is  then  distilled  off, 
the  flasks  dried  in  a  water  oven  at  100°  C.  to  constant 
weight,  cooled  and  weighed.     The  method  is  apt  to 


i  For  tests  for  artificial  coloring  mattepin  oleomargarine,  see  Olrc. 
629,  Oom.  of  Internal  Rev.,  Treasury  Dept. 


Chemical  Analysis  of  Milk  and  Its  Products.    241 

too  low  results  and,  therefore,  not  to  be  preferred  to 
the  Babcock  test  for  cheese  (105). 

287.  c.  Casein  (total  nitrogenX6.25).  About  2  grams 
of  cheese  are  weighed  out  on  a  watch  glass  and  trans- 
ferred to  a  Jena  nitrogen  flask,  and  the  nitrogen  in  the 
sample  determined  according  to  the  Kjeldahl  method 
(253)  ;  the  percentage  of  nitrogen  multiplied  by  6.25 
gives  the  total  nitrogenous  components  of  the  cheese. 

288.  d.  Ash.    The  residue  from  the  water  determina- 
tion is  taken  for  the  ash ;  it  is  preferably  set  fire  to,  in 
the  same  manner  as  explained  under  determination  of 
ash  in  butter    (270),  before  it  is  placed  in  the  muffle 
oven  and  incinerated.     The  increase  in  the  weight  above 
that  of  the  empty  dish-f-asbestcs,  gives  the  amount  of 
ash  in  the  sample  weighed  out. 

289.  e.  Other  constituents.    The  sum  of  the  percent- 
ages of  water,  fat,  casein  and  ash,  subtracted  from  100, 
will   give  the  per  cent,   of  other  constituents,   organic 
acids,- milk  sugar,  etc.,  in  the  cheese. 

DETECTION  OF  OLEOMARGARINE  CHEESE  ("FILLED" 
CHEESE.  ) 

290.  About  25  grams  of  finely-divided  cheese  are  ex- 
tracted with  ether  in  a  Caldwell  extractor  or  a  paper 
extraction  cartridge;  the  ether  is  distilled  off,  and  the 
fat  dried  in  the  water  oven  until  there  is  no  further 
loss  in  weight.     5.75  cc.  of  the  clear  fat  are  then  meas- 
ured into  a  250  cc.  saponification  flask  and  treated  ac- 
cording to  the  Reichert-Wollny  method,  as  already  ex- 
plained under  Detection  of  Artificial  Butter  (282). 1 

i:See:Arb.  Kals.  Ges.-Amt.,  14,  506-598 
6 


242  Testing  MUk  and  Its  Products. 

TESTS  FOR  ADULTERATION  OF  MILK  AND  CREAM. 

291.  The  nitric  acid  test  may  prove  useful  as  cor- 
roborating evidence  that  a  sample  of  milk  has  been 
watered  (126).  Normal  fresh  milk  does  not  contain 
nitrates,  while  common  well-water,  particularly  on 
farms  where  precautions  to  guard  against  contamina- 
tion of  the  water  supply  have  not  been  taken,  in  gen- 
eral contains  appreciable  amounts  of  nitrates,  nitrites 
and  ammonia  compounds,  and  watered  milk  will,  there- 
fore, in  such  cases  also  contain  nitrates.1  The  method 
for  detection  of  small  amounts  of  nitrates  in  milk,  as 
given  by  Richmond2  is  as  follows :  Place  a  small  quan- 
tity of  diphenylamin  at  the  bottom  of  a  porcelain  dish, 
and  add  to  it  about  1  cc.  of  pure  H2S04  (cone.)  ;  allow 
a  few  drops  of  the  milk  serum  (obtained  by  adding  a 
little  acetic  acid  to  the  milk  and  warming)  to  flow  down 
the  sides  of  the  dish  and  over  the  surface  of  the  acid. 
If  a  blue  color  develops  in  the  course  of  ten  minutes, 
though  it  may  be  faint,  it  shows  the  presence  of  nitrates ; 
after  ten  minutes  a  reddish-brown  color  is  always  de- 
veloped from  the  action  of  the  acid  on  the  serum. 
There  should  be  no  difficulty  in  detecting  an  addition  of 
10  per  cent,  of  water  to  the  milk  by  this  test,  if  the 
water  added  contained  5  parts  of  nitric  acid,  or  more, 
per  100,000. 

The  following  test  for  nitric  acid  is  proposed  by  Mc- 
Kay and  Bouska:  About  5  cc.  of  milk  is  placed  in  a 
test  tube.  Some  Kaniss'  reagent  (about  1  part  formal- 

1  Uffelmann,  Deutsche  Vierteljahresschr.  f.  off.  Ges.-pfl.  15,   p.  »>rc',. 

2  The  Analyst,  1893,  p.  272. 


Chemical  Analysis  of  Milk  and  Its  Products.    243 

dehyd  in  500  cc.  G.  P.  H2S04)  is  poured  down  the  side 
of  the  tube  so  it  will  form  a  layer  under  the  milk.  If 
nitrates  or  nitrites  are  present,  a  violet  ring  will  form 
at  the  place  of  contact.  This  is  Hehner's  test  for  for- 
maldehyd  reversed,  see  (304). 

292.  Besides  by  the  methods  given  in  the  preceding 
(pp.  109-115),  watering  or  skimming  of  milk  may  be  de- 
tected by  determining  the  specific  gravity  of  a,  the  skim 
milk,  b,  the  milk  serum,  and  c,  the  whey. 

a.'  Specific  gravity  of  skim  milk.  The  milk  is  set  in  a  flat 
porcelain  or  glass  dish  for  12-24  hours  in  a  cold  room;  the  layer 
of  cream  formed  is  then  skimmed  off,  and  the  sp.  gr.  of  the  skim 
milk  determined  at  60°  F.  Skim  milk  has  a  sp.  gr.  of  .002  to 
.0035  (2  to  3.5  lactometer  degrees)  above  that  of  the  correspond- 
ing whole  milk;  a  smaller  difference  than  this  indicates  that  the 
milk  was  skimmed.  If  both  skimming  and  watering  had  been 
practiced,  the  difference  given  above  might  be  obtained,  but  the 
analysis  of  the  milk  would  in  such  case  easily  disclose  the  adul- 
teration. 

b.  Specific    gravity  of  the  milk    serum.      To   100   cc.   milk  2 
cc.  of  20  per  cent.-acetic  acid  are  added,  and  the  mixture  heated 
in  a  covered  beaker  or  closed  flask  for  5-10  min.  on  a  water -bath 
at  55-65°  C.     After  cooling,  the  milk  serum  is  filtered  off  and  its 
sp.  gr.  determined  at  60°  F.     In  case  of  pure  milks,  the  sp.  gr. 
of  the  milk  serum  (at  60°)  will  come  above  1.0270.     Serum  from 
normal  milk  contains   6.3  to   7.5   per   cent,   solids   and  .22  to   .28 
per   cent,    fat;    by  the   addition   of   10    per   cent,    of   water,    the 
solids  in  the  serum  are  lowered  .3  to  .5  per  cent.,  and  the  sp.  gr., 
.0005.1 

c.  Specific  gravity  of  whey.     500  cc.  of  milk  are  warmed  in 
water  of  40-50°   C.  until  its  temperature  is  35°  C.;    one-half  cc. 
of  rennet  extract    (12-15  drops)    is   added,   and  the  milk  stirred 
thoroughly.     After  allowing  the  curd  to  solidify  for  10  minutes, 
it  is  cut  and  the  whey  filtered  off  through  several  layers  of  cheese 
cloth.     The  whey  must  be  clear;    it  is  cooled  to  60°  F.  and  its 

1  Konig,  Menschl,  Nahrungsmittel,  II,  p.  276. 


244  Testing  Milk  and  Its  Products. 

sp.  gr.  determined.  The  sp.  gr.  of  whey  from  normal  milk  ob- 
tained in  the  manner  given  will  range  between  1.027  and  1.031. 
A  sp.  gr.  of  1.026  or  below  indicates  watering.  An  addition  of 
4  per  cent,  of  water  lowers  the  sp.  gr.  of  the  whey  about  1  lac- 
tometer degree.1 

293.  Detection  of  coloring  matter.     Milk  which  has 
been  watered  cr  skimmed,  or  both,  is  sometimes  further 
adulterated  by  unscrupulous  milk  dealers  by  an  addi- 
tion of  a  small  quantity  of  cheese  color;  this  will  mix 
thoroughly  with  the  milk,  and,  if  added  judiciously,  will 
impart  a  rich  cream  color  to  it.     The  presence  of  for- 
eign coloring  matter  in  milk  is  easily  shown  by  shaking 
10  cc.  of  the  milk  with  an  equal  quantity  of  ether;  on 
standing,  a  clear  ether  solution  will  rise  to  the  surface; 
if  artificial  coloring  matter  has  been  added  to  the  milk, 
the  solution  will  be  yellow  colored,  the  intensity  of  the 
color   indicating   the    quantity   addded;   natural     fresh 
milk  will  give  a  colorless  ether  solution. 

A  method  given  by  Wallace2  is  claimed  to  detect  one 
part  of  coloring  matter  in  100,000  of  milk. 

Inorganic  coloring  matter  like  chromates  and  bi-chro- 
mates  have,  although  fortunately  rarely,  been  used  to 
impart  a  rich  color  to  adulterated  milk  or  poor  cream. 
Chromates  may  be  detected  by  the  reddish  yellow  color 
produced  when  a  little  2  per  cent. -silver  nitrate  solution 
is  added  to  a  few  cubic  centimeters  of  the  milk. 

294.  Detection  of  pasteurized  milk  or  cream.   Prof. 
Storch,  of  Copenhagen,  Denmark,3  in  1898,  published  a 
simple  method  for  ascertaining   whether  milk,   cream, 

1  Slats,  Unters.  landw.  wicht.  Stoffe,  p.  88. 

2  N.  J.  Dairy  Commissioner,  report.  1896,  p.  36. 
8  40th  report,  Copenhagen  experiment  station. 


Chemical  Analysis  of  Milk  and  Its  Products.    245 

or  other  dairy  products  have  been  heated  to  at  least 
176°  F.  (80°  C.).  The  test  is  made  as  follows:  A 
teaspoonful  of  the  milk  is  poured  into  a  test  tube,  and 
1  drop  of  a  weak  solution  of  peroxid  of  hydrogen  (2 
per  cent.)  and  2  drops  of  a  paraphenylenediamin-solu- 
tion  (2  per  cent.)  are  added.  The  mixture  is  then 
shaken;  if  a  dark  violet  color  appears  at  once,  the  milk 
has  not  been  heated,  or  at  any  rate  not  beyond  176°  P. 
If  a  sample  of  butter  is  to  be  examined,  25  grams  are 
placed  in  a  small  beaker  and  melted  by  being  placed  in 
water  of  60°  C.  The  clear  butter  fat  is  poured  off,  and 
the  remaining  liquid  is  diluted  with  an  equal  volume  of 
wrater.  The  mixture  thus  obtained  is  examined  as  in 
case  of  milk. 

Guaiacum  tincture  has  also  been  recommended  for  the 
detection  of  pasteurized  cream  or  milk;  this  solution  is 
easily  obtained,  keeps  well,  and  is  convenient  to  use 
(McKay). 

295.  Boiled  milk.     The  preceding  tests  will  serve  to 
distinguish  between  raw  and  boiled  milk,  and  also  to 
ascertain  if  milk  has  been  adulterated  with  diluted  con- 
densed milk.     To  what  extent  such  an  adulteration  can 
be  practiced  without  being  detected  by  this  or  similar 
tests,  has  not  been  determined,  but  if  a  control  test  be 
made  at  the  same  time  with  a  sample  of  milk  of  known 
purity,  a  small  admixture  of  boiled   (or  diluted  con- 
densed) milk  can  doubtless  be  detected.1 

296.  Gelatine  in   cream.     This  method  of  adultera- 
tion is  sometimes  practiced  in  the  city  cream  trade,  to 

1  See  also  Slats,  Unters.  landw.  wicht.  Stoffe,  p.  60,  and  Molkerei-Ztg. 
(Hildesheirn),  1899,  p.  677. 


246  Testing  Milk  and  Its  Products. 

impart  stiffness  and  an  appearance  of  richness  to  the 
cream.  To  detect  the  gelatine,  a  quantity  of  the  sus- 
pected cream  is  mixed  with  warm  water,  and  acetic  acid 
is  added  to  precipitate  the  casein  and  fat  (1.5  cc.  of  10 
per  cent.-acetic  acid  per  10  cc.  of  cream  is  sufficient). 
The  precipitate  is  filtered  off,  and  a  few  drops  of  a 
strong  tannin  solution  are  added  to  the  clear  filtrate. 
Pure  cream  will  give  a  slight  precipitate,  while  in  the 
presence  of  gelatine  a  copious  precipitate  will  come 
down. 

The  picric-acid  method  has  also  been  proposed  for 
the  detection  of  small  quantities  of  gelatine  in  cream.1 

297.  Starch  in   cream.     Starch  is  mentioned  in  the 
dairy  literature  as  an  adulterant  of  milk  and  cream.   It 
is  doubtful,  however,  if  it  is  ever  used  for  this  purpose 
at  the  present  time.     In  the  case  of  ice-cream,  on  the 
other  hand,   a  small  quantity  of  corn  starch  is  often 
added  to  thicken  the  milk  used.     It  may  in  such  a  case 
be  readily  detected  by  means  of  the  iodin  reaction.     A 
solution  of  iodin  will  produce  a  deep  blue  color  in  the 
presence  of  starch ;  a  small  amount  of  iodin  is  taken  up 
by  the  cream  before  the  blue  coloration  appears. 

298.  Macroscopic  impurities  (particles  of  hay,  litter, 
woolen  or  cotton  fibres,  dung,  etc.).     These  impurities 
may  be  separated  by  repeated  dilution  of  the  milk  with 
pure  distilled  water,  leaving  the  mixture  undisturbed 
for  a  couple  of  hours  each  time  before  the  liquid  is 
syphoned   off.     When   the  milk  has  been   entirely   re- 
moved in  this  manner,  the  residue  is  filtered  off,  dried 

1  The  Analyst,  1897,  p.  820. 


Chemical  Analysis  of  Milk  and  Its  Products.    247 

and  weighed.  A  quart  of  milk  or  cream  should  not 
give  any  visible  sediment  on  standing  for  several  hours. 
A  very  simple  and  striking  method  of  showing  dirt 
in  milk  has  been  suggested  by  Gerber.  About  a  pint  of 
milk  is  poured  into  an  inverted  bottomless  long-necked 
bottle,  over  the  mouth  of  which  a  piece  of  linen  is  tied. 
The  milk  will  filter  through  this  cloth,  leaving  the  dirt 
en  it.  When  the  milk  has  run  through,  the  cloth  is 
taken  off  and  can  be  shown  to  the  producer  of  the  milk.1 

DETECTION  OF  PRESERVATIVES  IN  DAIRY  PRODUCTS. 

299.  a.  Boracic   acid    (borax,    borates,    preservaline, 
etc.).     100  cc.  of  milk  are  made  alkaline  with  a  soda 
or  potash  solution,  and  then  evaporated  to  dryness  and 
incinerated.     The  ash  is  dissolved  in  water  to  which  a 
little  hydrochloric  acid  has  been  added,  and  the  solu- 
tion filtered.     A  strip  of  turmeric  paper  moistened  with 
the  filtrate  will  be  colored  reddish  brown  when  dried  at 
100°  C.  on  a  watch  glass,  if  boracic  acid  is  present. 

If  a  little  alcohol  is  poured  over  the  ash  to  which  con- 
centrated sulfuric  acid  has  been  added,  and  fire  is  set 
to  the  alcohol;  after  a  little  while  this  will  burn  with  a 
yellowish  green  tint,  especially  noticeable  if  the  ash  is 
stirred  with  a  glass  rod  and  when  the  flame  is  about  to 
go  out. 

300.  The  following  modification  of  the  first  test  given  is  said 
to  show  the  presence  of  only  a  thousandth  of  a  grain  of  borax 
in  a  drop  of  milk   (about  .15  per  cent.)  :* 

Place  in  a  porcelain  dish  one  drop  of  milk  with  two  drops  of 
strong  hydrochloric  acid  and  two  drops  of  saturated  turmeric 

1  Hoard's  Dairyman,  Nov.  29,  1907. 

2  N.  J.  Dairy  Commissioner,  report  1896,  p.  37. 


248  Testing  Milk  and  Its  Products. 

tincture;  dry  this  on  the  water  bath,  cool  and  add  a  drop  of 
ammonia  by  means  of  a  glass  rod.  A  slaty  blue  color  changing 
to  green  is  produced  if  borax  is  present.1 

301.  b.  Bi-carbonate    of   soda.      100   cc.    of   milk  to 
which  a  few  drops  of  alcohol  are  added,  are  evaporated 
and  carefully  incinerated;  the  proportion  of  carbonic 
acid  in  the  ash  as  compared  with  that  of  milk  of  known 
purity  is  determined.     If  an  apparatus  for  the  deter- 
mination of  carbonic  acid  is  available,  like  the  Scheibler 
apparatus,  etc.,  the  per  cent,  of  carbonic  acid  per  gram 
of  ash   (and  quart  of  milk)   can  be  easily  ascertained. 
Normal  milk  ash  contains  only  a  small  amount  of  car- 
bonic acid  (less  than  2  per  cent.),  presumably  formed 
from  the  citric  acid  of  the  milk  in  the  process  of  incin- 
eration. 

The  following  qualitative  test  is  easily  made:  To  10 
cc.  of  milk  add  10  cc.  of  alcohol  and  a  little  of  a  one 
per  cent,  rosolic-acid  solution.  Pure  milk  will  give  a 
brownish  yellow  color;  milk  to  which  soda  has  been 
added,  a  rose  red  color.  A  control  experiment  with 
milk  of  known  purity  should  be  made. 

302.  c.  Fluorids.     100  cc.  of  milk  are  evaporated  in 
a  platinum  or  lead  crucible,  and  incinerated;  the  ash  is 
made  strongly  acid  with  concentrated  sulfuric  acid.    If 
fluorids  are  present  hydrofluoric  acid  will  be  generated 
on  gentle  heating  and  will  be  apparent  from  its  etching 
a  watch  glass  placed  over  the  crucible.2 

303.  d.  Salicylic   acid    (salicylates,   etc.}.     20  cc.   of 
milk  are  acidulated  with  sulfuric  acid  and  shaken  with 

1  See  also  151. 

8  Chromates  in  dairy  products  may  be  readily  determined  by  the  use 
of  a  silver-nitrate  solution,  see  Molkerei-Ztg.  (Berlin)  1899,  p.  608. 


Chemical  Analysis  of  Milk  and  Its  Products.    249 

ether;  the  ether  solution  is  evaporated,  and  the  residue 
treated  with  alcohol  and  a  little  iron-chlorid  solution; 
a  deep  violet  color  will  be  obtained  in  the  presence  of 
salicylic  acid. 

304.  e.  Formaldehyde  (a  forty-per  cent,  solution  in 
water) . 

*  The  following  method  by  Hehner  is  stated  to  show 
the  presence  of  one  part  of  formaldehyde  in  200,000 
parts  of  milk :  the  milk  is  diluted  with  an  equal  volume 
of  water,  and  strong  H2S04  (sp.  gr.  1.82-1.84)  is  added. 
A,  violet  ring  is  formed  at  the  junction  of  the  two 
liquids  if  formaldehyde  is  present ;  if  not,  a  slight  green- 
ish tinge  will  be  seen.  The  violet  color  is  not  obtained 
with  milk  containing  over  .05  per  cent,  formaldehyde.1 

The  same  color  reaction  is  obtained  in  the  Babcock 
test  and  is  easily  recognized  by  persons  familiar  with 
milk  testing  when  their  attention  has  once  been  called 
to  the  characteristic  color. 

An  adulteration  of  milk  with  formaldehyde  may  be 
readily  detected  by  the  following  method,  which  will 
show  the  presence  of  only  a  trace  of  formaldehyde  in 
the  milk.  5  cc.  of  milk  is  measured  into  a  white  porce- 
lain dish,  and  a  similar  quantity  of  water  added.  10 
cc.  of  HC1  containing  a  trace  of  Fe2Cl6  is  added,  and 
the  mixture  is  heated  very  slowly.  If  formaldehyde  is 
present,  a  violet  color  will  be  formed. 

1  Ohem.  News,  1896,  No.  71;  Milchzeitung,  1896,  491;  1897,  40,  667;  The 
Analyst,  1895.  152,  154,  157;  1896,  285. 


GOVERNMENT  STANDARDS  OF    PURITY   FOR 
MILK  AND  ITS  PRODUCTS.1 


a.     MILKS. 

1.  Milk  is  thei  fresh,  clean,  lacteal  secretion  obtained  by   the 
complete    milking    of    one    or    more    healthy    cows,    properly    fed 
and  kept,  excluding  that  obtained  within  fifteen  days  before  and 
ten  days  aftetr  calving,  and  contains  not  less  than  eight  and  one- 
half   (8.5)    per  cent,   of  solids  not  fat,  and  not  less  than  three 
and  one-quarter   (3.25)  per  cent,  of  milk  fat. 

2.  Blended  milk  is  milk  modified  in  its  composition  so  as  to 
have  a  definite  and  stated,  percentage  of  one  or  more  of  its  con- 
stituents. 

3.  Skim  milk  is  milk  from  which  a  part  or  all  of  the  cream 
has  been  removed  and  contains  not  less  than  nine  and  one-quarter 
(9.25)  per  cent,  of  milk  solids. 

4.  Pasteurized  milk   is  milk  that  has  been  heated  below  boil- 
ing but  sufficiently  to  kill  most  of  the  active  organisms  present 
and  immediately  cooled  to  50°  Fahr.  or  lower. 

5.  Sterilized  milk    is  milk   that  has  been  heated  at  the  tem- 
perature of  boiling  water  or  higher   for   a  length   of  time  suffi- 
cient to  kill  all  organisms   present. 

6.  Condensed  milk,  evaporated  milk,  is   milk   from  which   a 
considerable  portion  of  water  has  been  evaporated   and  contains 
not  less  than  twenty-eight  (28)  per  cent,  of  milk  solids,  of  which 
not   less    than    twenty-seven    and   five-telnths    (27.5)    per    cent,    is 
milk  fat. 

7.  Sweetened  condensed  milk  is  milk   from  which   a   consid- 
erable portion  of  water  has  been  evaporated  and  to  which  sugar 
(sucrose)    has  been   added,   and    contains  not   less   than    twenty- 
eight    (28)    per    cent,    of    milk    solids,    of    which    not    less    than 
twenty-seven  and  five-tenths   (27.5)    per  cent,  is  milk  fat. 

1  Circular  No.  19,  Office  of  the  Secretary,  U.  8.  Dept.  of  Agriculture, 
June  26, 1906. 


Government  Standards   of  Purity.  251 

8.  Condensed  skim  milk  is  skim  milk  from  which  a  consid- 
erable portion  of  water  has  been  evaporated. 

9.  Buttermilk    is  the  product  that  remains  when  butter  is  re- 
moved from  milk  or  cream  in  the  process  of  churning. 

10.  Goat's  milk,  ewe's  milk,  etc.,  are  the  fresh,   clean,  lac- 
teal   setcretions,   free   from    colostrom,   obtained   by    the    complete 
milking  of   healthy   animals   other   than   cows,   properly   fed   and 
kept,  and  conform  in  name  to  the  species  of  animal  from  which 
they  are  obtained. 

b.     CREAM. 

1.  Cream  is    that    portion   of   milk,   rich    in   milk    fat,    which 
rises  to  thei  surface  of  milk  on  standing,  or  is  separated  from  it 
by   centrifugal   force,   is   fresh   and   clean  and   contains   not   less 
than  eighteen  (18)   per  cent,  of  milk  fat. 

2.  Evaporated  cream,  clotted  cream,  is   cream   from  which 
a  considerable  portion  of  watetr  has  been  evaporated. 

C.      MILK  FAT  OB  BUTTER  FAT. 

1.  Milk  fat,  butter  fat,  is  the  fat  of  milk  and  has  a  Eeich- 
ert-Meissl  number  not  less  than  twenty-four  (24)  and  a  specific 
gravity  of  not  less  than  0.905  (  ^^\ 

V  40    O.  / 

d.      BUTTER. 

1.  Butter    is  the   clean,   non-rancid  product  made  by   gather- 
ing in  any  manner   the  fat  of  fresh  or  ripened  milk  or  cream 
into   a  mass,   which  also   contains   a   small  portion  of   the   other 
milk    constituents,   with   or    without    salt,    and    contains   not   less 
than  eighty-two  and  fivehtenths  (82.5)  per  cent,  of  milk  fat.     By 
acts   of   Congress   approved   August   2,    1886,    and  May   9,    1902, 
butter  may  also  contain  added  coloring  matter. 

2.  Renovated  butter,  process  butter,  is   the   product   made 
by  melting  butter  and  reworking,  without  the  addition  or  use  of 
chemicals    or    any    substances    except    milk,    cream,    or    salt,    and 
contains  not  more  than  sixteen    (16)   per  cent,   of  water  and  at 
least  eighty-two  and  five-tenths    (82.5)    per  cent,  of  milk  fat. 


252  Testing  Milk  and  Its  Products. 

e.    CHEESE. 

1.  Cheese  is  the!  sound,  solid,  and  ripened  product  made  from 
milk  or  cream  by  coagulating  the  casein  thereof  with  rennet  or 
lactic   acid,   with  or  without   the  addition   of   ripening  ferments 
and  seasoning,  and  contains,  in  the  water-free  substance,  not  less 
than  fifty   (50)   per  cent,  of  milk  fat.     By  act  of  Congress,  ap- 
proved  June   6,    1896,    cheese   may    also    contain   added    coloring 
matter. 

2.  Skim  milk  cheese  is  the  sound,  solid,  and  ripened  product, 
made  -  from   skim  milk   by   coagulating    the    casein   thereof    with 
rennet  or  lactic  acid,  with  or  without  the   addition  of  ripening 
ferments   and  seasoning. 

3.  Goat's  milk  cheese,  ewe's  milk  cheese,  etc.,  are    the 
sound,    ripened   products   made    from   the   milks    of    the,    animals 
specified,  by  coagulating  the  casein  thereof  with  rennet  or  lactic 
acid,    with    or    without   the    addition    of   ripening   ferments    and 
seasoning. 

f.      ICE    CREAMS. 

1.  Ice  cream  is  a  frozen  product  madei  from  cream  and  sugar, 
with  or  without  a  natural  flavoring,  and  contains  not  less  than 
fourteen   (14)  per  cent,  of  milk  fat. 

2.  Fruit  ice  cream    is   a   frozen   product   made   from    cream, 
sugar,  and  sound,  clean,  mature  fruits,  and  contains  not  less  than 
twelve  (12)  per  cent,  of  milk  fat. 

3.  Nut  ice  cream     is    a    frozen    product    made    from    cream, 
sugar,   and   sound,   non-rancid   nuts,   and    contains   not   less   than 
twelve  (12)   per  cent,  of  milk  fat. 

g.      MISCELLANEOUS    MILK    PRODUCTS. 

1.  Whey   is   the  product  remaining  after  the  removal  of   fat 
and  casein  from  milk  in  the  process  of  cheese-making. 

2.  Kumiss  is  the  product  made  by  the  alcoholic  fermentation 
of  mare's  or  cow's  milk. 


STANDARDS  FOR  BABCOCK  GLASSWARE. 
(Holland;  adopted  by  Eastern  Experiment  Stations.) 


SEC.  1.  The  unit  of  graduation  for  all  Babcock  glassware 
shall  be  the  true  cubic  centimeter  (.998877  gram  of  water  at 
40°  C.). 

(a)  With  bottles,  the  capacity  of  each  per  cent,  on  the  scale 
shall  be  two-tenths    (0.20)    cubic  ceoitimeter. 

(b)  With  pipettes  and  acid  measures  the  delivery  shall  be  the 
intent  of  the  graduation  and  the  graduation  shall  be  read  with 
the  bottom  of  the  meniscus  in  line  with  the  mark. 

SEC.  2.  The  official  method  for  testing  bottles  shall  be  cali- 
bration with  mercury  (13.5471  grams  of  clean,  dry  mercury  at 
20°  C.,  carefully  weighed  on  analytical  balances,  to  be  equal  to 
5  per  cent,  on  the  Babcock  scale),  the  bottles  being  previously 
filled  to  zero  with  mercury. 

SEC.  3.  Optional  methods. — The  mercury  and  cork,  alcohol  and 
burette,  and  alcohol  and  brass  plunger  methods  may  be  employed 
for  the  rapid  testing  of  Babcock  bottles,  but  the  accuracy  of  all 
questionable  bottles  shall  be  determined  by  the  official  method. 

SEC.  4.  The  official  method  for  testing  pipettes  and  acid 
measures  shall  be  calibration  by  measuring  in  a  burette  the 
quantity  of  water  (at  20°  C.)  delivered. 

SEC.  5.  The  limits  of  error. — (a)  For  Babcock  bottles  shall 
be  the  smallest  graduation  on  the  scale,  but  in  no  case  shall  it 
exceed  five-tenths  (-0.50)  per  cent.,  or  for  skim  milk  bottles  one- 
hundredth  (0.01)  per  cent. 

(b)  For   full-quantity    pipettes,   it   shall    not   exceed    one- tenth 
(0.10)    cubic    centimeter,    and    for    fractional    pipettes,    five-hun- 
dredths   (0.05)    cubic  centimeter. 

(c)  For   acid   measures   it  shall  not   exceed   two-tenths    (0.20) 
cubic    centimeter. 


APPENDIX. 


Table  I.     Composition  of  milk- and  its  products. 


No.  of 
analyses 

Water 

Fat 

Casein 
and 
albumen 

Milk 
sugar 

Ash 

Authority 

Cow's  milk  

793 

pr.  ct. 

87.17 
87.75 
87.10 
86.48 
87.10 
74.57 
68.82 
73.90 
90.43 
90.52 
90.30 
90.12 
91.67 
93.38 
93.12 

58.99 

25.61 
11.95 
12.93 
13.08 
13.07 
11.57 
36.33 
38.00 
36.84 
34.38 

32.06 
39.79 
46.00 
50.5 

pr.  ct. 

3.69 
3.40 
3.90 
4.20 
3.90 
3.59 
22.66 
17.60 
.87 
.32 
.10 
1.09 
.27 
.32 
.27 

12.42 

10.35 

84.27 
84.53 
84.26 
85.24 
84.70 
40.71 
30.25 
33.83 
32.71 

34.43 
23.92 
11.65 
1.2 

pr.  ct. 

3.55 
3.50 
3.201 
3.512 
3.40 
17.  644 
3.76 

pr.  ct. 

4.88 
4.60 
5.10 

pr.  ct. 

.71 
.75 
.70 
3.71 
.75 
1.56 
.53 
.62 
.70 

Kdnig5 
Fleischmann 
Van  Slyke 
Holland6 
Richmond 

Konig5 

a 

Holland6 
Konig5 
Holland6 
Van  Slyke 
Konig5 
Holland6 
Konig5 
Van  Slyke 

Konig5 

1  1 

Well 

Konig5 

1  1 

Won 

Farrington 

Konig5 

a 

Van  Slyke 
Drew 

Shutt 

Konig5 

n 

Storch 

it         a 

a         n 

5,552 
2,173 
200,000 
42 
43 
203 
56 
354 

a         it 

1  1         a 

4.85 
2.67 
4.23 

Colostrum  milk  

Cream 

Cream    Cooley      

Skim  milk  (gravity)  .  . 

a        a            a 

Skim  milk    (centrifugal) 
Butter  milk   

3.26 

4.74 

3.55 
4.03 

5.25 
4.04 

.80 

.72 

57 
31 

46 

tt          it 

Whey 

.86 
.81 

11.92 

11..  79 
1.5 

.61 
.81 
l.( 

.< 

18.84 
25.35 
23.72 
26.38 

28.00 
29.67 
34.06 
43.1 

4.79 
5. 

14.49 

50.06 
56 

.68 
.66 
)7 
)5 
1.02 
1.43 
5. 
2.9$ 

5. 
1.79 
3.42 

.65 

30 

2.18 

2.19 
2.58 
1.25 
1.19 
.12 
2.78 
3.10 
4.97 
61 
3.58 

51 

4.73 
4.87 
5.2 

Condensed  milk, 
(no  sugar  added).  .  . 
Condensed  milk, 
(sugar  added)  .  . 

36 

64 
1,676 
10 
11 
242 
350 
127 
143 

Butter,  salted  

sweet  cream  .  . 
sour  cream  .  .  . 
"        unsalted  
"      World's  Fair,  1893 
Cheese,  cream     .  . 

full  cream  
cheddar,  green 
"        cheddar,  cured 
World's  Fair 
Mam'th,  1893 
tl        half-skim  .  .  .  . 
"        skim 

27 

1 
21 
41 

centrifugal  skim.. 

1  .70  per  cent,  albumen. 

2  Forty-two  analyses. 

3  Eight  analyses. 


4  13.60  per  cent,  albumen. 
•*>  Mostly  European  samples. 
6  Massachusetts'  samples. 


256 


Testing  Milk  and  Its  Products. 


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Appendix. 


257 


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258 


Testing  Milk  and  Its  Products. 


Table  III.     Quevenne  lactometer  degrees  corresponding  to 
N.  Y.  Board  of  Health  degrees.     (See  p.  104) 


Bd.  &  Health 
decrees. 

Quevenne 
scale. 

Bd.  of  Health 
degrees. 

Quevenne 
scale. 

Bd.  of  Health 
degrees. 

Quevenne 
scale. 

60 

17.4 

81 

23.5 

101 

29.3 

61 

17.7 

82 

23.8 

102 

29.6 

62 

18.0 

83 

24.1 

103 

29.9 

63 

18.3 

84 

24.4 

104 

30.2 

64 

18.6 

85 

24.6 

105 

30.5 

65 

18.8 

86 

24.9 

106 

30.7 

66 

19.1 

87 

25.2 

107 

31.0 

67 

19.4 

88 

25.5 

108 

31.3 

68 

19.7 

89 

25.8 

109 

31.6 

69 

20.0 

90 

26.1 

110 

31.9 

70 

20.3 

91 

26.4 

111 

32.2 

71 

20.6 

92 

26.7 

112 

32.5 

72 

20.9 

93. 

27.0 

113 

32.8 

73 

21.2 

94 

27.3 

114 

33.1 

74 

21.5 

95 

27.6 

115 

33.4 

75 

21.7 

96 

27.8 

116 

33.6 

76 

22.0 

97 

28.1 

117 

33.9 

77 

22.3 

98 

28.4 

118 

34.2 

78 

22.6 

-    99 

28.7 

119 

34.5 

79 

22.9 

100 

29.0 

120 

34.8 

80 

23.2 

Table  IV.    Value  of  m*-m  for  sp.  gr.  from  1.019  to  1.0369. 


Sp.gr.  (g)  = 

0.0000 

0.0001 

0.0002 

0.0003 

0.0004 

0.0005 

0.0006 

0.0007 

0.0008 

0.0009 

1.019 

1.864 

1.874 

1.884 

1.894 

1.903 

1.913 

1.922 

1.932 

1.941 

1.951 

1.020 

1.961 

1.970 

1.980 

1.990 

1.999 

2.009 

2.018 

2.028 

2.038 

2.047 

1.021 

2.057 

2.066 

2.076 

2.086 

2.095 

2.105 

2.114 

2.124 

2.133 

2.143 

L022 

2.153 

2.162 

2.172 

2.181 

2.191 

2.200 

2.210 

2.220 

2.229 

2.239 

1.023 

2.249 

2.258 

2.267 

2.277 

2.286 

2.296 

2.306 

2.315 

2.325 

2.334 

1.024 

2.344 

2.353 

2.363 

2.372 

2.382 

2.391 

2.401 

2.410 

2.420 

2.430 

1.025 

2.439 

2.449 

2.458 

2.468 

2.477 

2.487 

2.496 

2.506 

2.515 

2.525 

1.026 

2.534 

2.544 

2.553 

2.563 

2.573 

2.582 

2.591 

2.601 

2.610 

2.620 

1.027 

2.629 

2.638 

2.648 

2.657 

2.667 

2.676 

2.686 

2.695 

2.705 

2.714 

1.028 

2.724 

2.733 

2.743 

2.752 

2.762 

2.771 

2.781 

2.790 

2.799 

2>09 

1.029 

2.818 

2.828 

2.837 

2.847 

2.356 

2.865 

2.875 

2.884 

2.893 

2.903 

1.030 

2.913 

2.922 

2.931 

2.941 

2.951 

2.960 

2.969 

2.979 

2.988 

2.997 

1.031 

3.007 

3.016 

3.026 

3.035 

3.044 

3.054 

3.063 

3.072 

3.082 

3.091 

1.032 

3.101 

3.110 

3.120 

3.129 

3.138 

3.148 

3.157 

3.166 

3.176 

3.185 

1.033 

3.195 

3.204 

3.213 

3.223 

3.232 

3.241 

3.251 

3.260 

3.269 

3.279 

1.034 

3.288 

3.298 

3.307 

3.316 

3.326 

3.335 

3.344 

3.354 

3.363 

3.372 

1.035 

3.382 

3.391 

3.400 

3.410 

3.419 

3.428 

3.438 

3.447 

3.456 

3.466 

1.036 

3.475 

3.484 

3.494 

3.503 

3.512 

3.521 

3.531 

3.540 

3.549 

3.559 

(See  directions  for  use,  p.  112) 


Appendix.  259 

Table  V.    Correction-table  for  specific  gravity  of  milk. 


2   • 

fSf 

Temperature  of  milk  (in  degrees  Fahrenheit). 

I! 

§2 

51 

52 

53 

54 

55 

53 

57 

58 

59 

60 

20 

19.3 

19.4 

19.4 

19.5 

19.6 

19.7 

19.8 

19.9 

19.9 

20.0 

21 

20.3 

20.3 

20.4 

20.5 

20.6 

20.7 

20.8 

20.9 

20.9 

21.0 

22 

21.3 

21.3 

21.4 

21.5 

21.6 

21.7 

21.8 

21.9 

21.9 

22.0 

23 

22.3 

22.3 

22.4 

22.5 

22.6 

22.7 

22.8 

22.8 

22.9 

23.0 

24 

23.3 

23.3 

23.4 

23.5 

2X6 

23.6 

23.7 

23.8 

23.9 

24.0 

25 

24.2 

24.3 

24.4 

24.5 

24.6 

24.6 

24.7 

24.8 

24.9 

25.0 

26 

25.2 

25.2 

25.3 

25.4 

25.5 

25.6 

25.7 

25.8 

25.9 

26.0 

27 

26.2 

26.2 

26.3 

26.4 

26,5 

26\6 

26.7 

26.8 

26.9 

27.0 

28 

27.1 

27.2 

27.3 

27.4 

27.5 

27.6 

27.7 

27.8 

27.9 

28.0 

29 

.  28.1 

28.2 

28.3 

28.4 

28.5 

28.6 

28.7 

28.8 

28.9 

29.0 

30 

29.1 

29.1 

29.2 

29.3 

29.4 

-M.6 

29.7 

29.8 

29.9 

30.0 

31 

30.0 

30.1 

30.2 

30,3 

30.4 

;;j.5 

30.6 

20.8 

30.9 

31.0 

32 

31.0 

31.1 

31.2 

31.3 

31.4 

31.5 

31.6 

31.7 

31.9 

32.0 

33 

31.9 

32.0 

32.1 

32.3 

3M 

32.5 

32.6 

32.7 

32.9 

33.0 

34 

32.9 

33.0 

33.1 

33.2 

33.3 

33.5 

33.6 

33.7 

33.9 

34.0 

35 

33.8 

33.9 

34.0 

34.2 

34.3 

34.5 

.• 

34.6 

34.7 

34.9 

35.0 

61 

62 

63 

64 

65 

66 

67 

68 

69 

70 

20 

20.1 

20.2 

20.2 

20.3 

20.4 

20.5 

20.6 

20.7 

20.9 

21.0 

21 

21.1 

21.2 

21.3 

21.4 

21.5 

21.6 

21.7 

21.8 

22.0 

22.1 

22 

22.1 

22.2 

22.3 

22.4 

22.5 

22.6 

22.7 

22.8 

23.0 

23.1 

23 

23.1 

23.2 

23.3 

23.4 

23.5 

23.6 

23.7 

23.8 

24.0 

24.1 

24 

24.1 

24.2 

24.3 

24.4 

24.5 

24.6 

24.7 

24.9 

25.0 

25.1 

25 

25.1 

25.2 

25.3 

25.4 

25.5 

25.6 

25.7 

25.9 

26.0 

26.1 

26 

26.1 

26.2 

26.3 

26.5 

26.6 

26.7 

26.8 

27.0 

27.1 

27.2 

27 

27.1 

27.3 

27.4 

27.5 

27.6 

27.7 

27.8 

28.0 

28.1 

28.2 

28 

28.1 

28.3 

28.4 

28.5 

28.6 

28.7 

28.8 

29.0 

29.1 

29.2 

29 

29.1 

29.3 

29.4 

29.5 

29.6 

29.7 

29.9 

30.1 

30.2 

30.3 

30 

30.1 

30.3 

30.4 

30.5 

30.7 

30.8 

30.9 

31.1 

31.2 

31.3 

31 

31.2 

31.3 

31.4 

31.5 

31.7 

31.8 

31.9 

32.1 

32.2 

32.4 

32 

32.2 

32.3 

32.5 

32.6 

32.7 

32.9 

33.0 

33.1: 

33.  3« 

33.4 

33 

33.2 

33.3 

33.5 

33.6 

33.8 

33.9 

34.0 

34.2 

34.3 

34.5 

34 

34.2 

34.3 

34.5 

34.6 

34.8 

34.9 

35.0 

35.2 

35.3 

35.5 

35 

35.2 

35.3 

35.5 

35.6 

35.8 

35.9 

36.1 

36.2 

36.4 

36.5 

DIRECTIONS.— Bring  the  temperature  of  the  milk  to  within  10°  of 
60°  F.  Take  the  reading  of  the  lactometer  and  f  hat  of  the  temperature  of 
the  milk;  find  the  iormer  in  the  first  vertical  column  of  the  table  and  the 
latter  in  the  first  horizontal  row  of  figures;  the  figure  where  the  horizontal 
and  vertical  columns  meet  is  the  corrected  lactometer  reading;  e.g.,  ob- 
served, 31.0  at  67°  F. ;  corrected  reading,  31.9. 


260 


Testing  Milk  and  Its  Products. 


Table  VI.  Per  cent,  of  solids  not  fat,  corresponding  to  0  to 
6  per  cent,  of  fat,  and  lactometer  readings  of  26  to 

36.     (See  directions  for  use,  p.  108.) 


« 

LACTOMETER  READINGS  AT  60°  F. 

o 

r 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

I* 

0 

6.50 

6.75 

7.00 

7.25 

7.50 

7.75 

8.00 

8.25 

8.50 

8.75 

9.00 

0 

0.1 

6.52 

6.77 

7.02 

7.27 

7.52 

/.77 

8.02 

8.27 

8.52 

8.77 

9.02 

0.1 

0  2 

6  54 

6  79 

7  04 

7  29 

7  54 

7  79 

8  04 

8  29 

8  54 

8  79 

9  04 

0.2 

0.3 

6.56 

6.81 

7.06 

7.31 

7.56 

7.81 

8.06 

8.31 

8.56 

8.81 

9.06 

0.3 

0.4 

6.58 

6.83 

7.08 

7.33 

7.58 

7.83 

8.08 

8.33 

8.58 

8.83 

9.08 

0.4 

0  5 

6  60 

6  85 

7  10 

7  35 

7  60 

7  a5 

8  10 

8  35 

8  60 

8  85 

9  10 

0.5 

0.6 

6.62 

6.87 

7.12 

7.37 

7.62 

7.87 

8.12 

8.37 

8.62 

8.87 

942 

0.6 

0.7 

6.64 

6.89 

7.14 

7.39 

7.64 

7.89 

8.14 

8.39 

8.64 

8.89 

9.14 

0.7 

0  8 

6  91 

7  16 

7  41 

7  68 

7  91 

8  16 

8  41 

8  66 

8  91 

9  16 

0  8 

0.9 

6.68 

6.93 

7.18 

7.43 

7.68 

7.93 

8.18 

8.43 

8.68 

8.93 

9.18 

0.9 

1.0 

6.70 

6.95 

7.20 

7.45 

7.70 

7.95 

8.20 

8.45 

8.70 

8.95 

9.20 

1.0 

1.1 

6.72 

6.97 

7.22 

7.47 

7.72 

7.97 

8.22 

8.47 

8.72 

8.97 

9.22 

1.1 

1.2 

H.74 

6.99 

7.24 

7.49 

7.74 

7.99 

8^24 

8.49 

8.74 

8.99 

9.24 

1.2 

1.3 

6.76 

7.01 

7.26 

7.51 

7.76 

8.01 

8.26 

8.51 

8.76 

9.01 

9.26 

1.3 

1  4 

6  78 

7  03 

7  28 

7  53 

7  78 

8  OS 

8  28 

8  53 

8  78 

9  03 

9  28 

1.4 

1.5 

6.80 

7.05 

7.30 

7.55 

7.80 

8.05 

8.30 

8.55 

8.80 

9.05 

9.30 

1.5 

1.6 

6.82 

7.07 

7.32 

7.57 

7.82 

8.07 

8.32 

8.57 

8.82 

9.07 

9.32 

l.C 

1.7 

6.84 

7.09 

7.34 

7.59 

7.84 

8.09 

8.34 

8.59 

8.84 

9.09 

9.34 

1.7 

1.8 

6.86 

7.11 

7.36 

7.61 

7.86 

8.11 

8.36 

8.61 

8.86 

9.11 

9.37 

1.8 

1.9 

6.88 

7.13 

7.38 

7.63 

7.88 

8.13 

8.38 

8.63 

8.88 

9.13 

9.39 

1.9 

2.0 

6.90 

7.15 

7.40 

7.65 

7.90 

8.15 

8.40 

8.66 

8.91 

9.16 

9.41 

2.0 

2.1 

6.92 

7.17 

7.42 

7.67 

7.92 

8.17 

8.42 

8.68 

8.93 

9.18 

9.43 

2.1 

2.2 

6.94 

7.19 

7.44 

7.69 

7.94 

8.19 

8.44 

8.70 

8.95 

9.20 

9.45 

2.2 

2.3 

6.96 

7.21 

7.46 

7.71 

7.96 

8.21 

8.46 

8.72 

8.97 

9.22 

9.47 

2.3 

2.4 

6.98 

7.23 

7.48 

7.73 

7.98 

8.23 

8.48 

8.74 

8.99 

9.24 

9.49 

2.4 

2.5 

7.00 

7.25 

7.50 

7.75 

8.00 

8.25 

8.50 

8.76 

9.01 

9.26 

9.51 

2.5 

2.6 

7.02 

7.27 

7.52 

7.77 

8.02 

8.27 

8.52 

8.78 

9.03 

9.28 

9.53 

2.6 

2.7 

7.04 

7.29 

7.54 

7.79 

8.04 

8.29 

8.54 

8.80 

9.05 

9.30 

9.55 

2.7 

2  8 

7  06 

7  SI 

7  5f> 

7  81 

8  Or> 

8  S1 

8  57 

8  8? 

)  07 

9  32 

9  57 

2  8 

2.9 

7.08 

7.33 

7.58 

7.83 

8.08 

8.33 

8.59 

8.84 

9.09 

9.34 

O.r,o 

2.9 

Appendix. 


261 


Table  VI.    Per  cent,  of  solids  not  fat  (Continued). 


LACTOMETER  READINGS  AT  60°  F. 

^ 

fl+j 

§~* 

S* 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

f«<M 

£ 

3.0 

7  10 

7  35 

7  60 

7  85 

8  10 

8  36 

8  61 

8  86 

9  11 

9  3r 

9.61 

3,0 

3.1 

7.12 

7.37 

7.62 

7.87 

8.13 

8.38 

8.6b 

8.88 

9.13 

9.38 

9.64 

3.1 

3.2 

7.14 

7.31 

7.64 

7.89 

8.15 

8.40 

8.65 

8.90 

9.15 

9.41 

9.66 

3.2 

3  3 

7  16 

7  41 

7  66 

7  99 

8  17 

8  49 

8  67 

8  99 

9  18 

9  43 

9  68 

3  3 

3.4 

7  18 

7  43 

7  69 

7  94 

8  If 

8  44 

8  69 

8  94 

9  ?,o 

9  45 

9.70 

3.4 

3.5 

7.20 

7.45 

7.71 

7.96 

8.21 

8.46 

8.71 

8.96 

9.22 

9.47 

9.72 

3.5 

3.6 

7.22 

7.48 

7.73 

7.9S 

8.23 

8.48 

8.73 

8.98 

9.24 

9.49 

9.74 

3.6 

3.7 

7.24 

7.50 

/  .75 

•s.OO 

3.25 

8.50 

8.75 

9.00 

9.26 

9.51 

9.7( 

3.7 

3.8 

7  W 

7  59 

7.  77 

8  02 

8  ?,7 

8  59 

8  77 

9  09 

9  9,S 

9  53 

9.78 

3.8 

3.9 

7.28 

7.54 

7'.  7^ 

8.04 

8.29 

8.C4 

8.79 

9.04 

9.30 

9.55 

9.80 

3.9 

4.0 

7  30 

7  5fi 

7  SI 

8  06 

8  31 

8  56 

8  81 

9  06 

9  39 

9  57 

9  83 

4  0 

4.1 
4.2 

7.32 
7.34 

7.58 
7.60 

r7.83 
7.85 

8.08 
8.10 

8.33 
S.35 

8.58 
8.60 

8.83 
3.85 

SSf 

(9.34 
9.36 

9.59 
9.62 

9.85 
9.87 

4.1 
4.2 

4.3 

7.36 

7.62 

7.87 

8.12 

8.37 

8.62 

8.88 

9.13 

9.38 

9.64 

9.89 

4.3 

4  4 

7  38 

7  64 

7  89 

8  14 

S  39 

8  64 

8  90 

9  15 

9  40 

9  f>(> 

9  91 

4  4 

4.5 

7  40 

7  66 

7  91 

8  16 

8  41 

S  60 

8  9° 

9  17 

9  49, 

9  (,8 

9  93 

4  5 

4.6 

7  43 

7  6S 

7  93 

8  18 

8  43 

8  6S 

S  94 

9  19 

9  44 

9  70 

9  95 

4  6 

4.7* 

7.45 

7.70 

7.95 

8.20 

S.45 

8.70 

8.96 

J.21 

9.46 

9.72 

9.97 

4.7 

4.8 

7  47 

7  79 

7  97 

8  29 

S  47 

8  79 

S  98 

9  93 

9  48 

9  74 

9  99 

4  8 

4.9 

7.49 

7.74 

7.99 

8.24 

3.49 

8.74 

9.00 

9.25 

9.50 

9.76 

10.01 

4.9 

5.0 

7.51 

7.76 

8.01 

8.26 

S.51 

8.76 

9  02 

9.27 

9.52 

9.78 

10.03 

5.0 

5.1 

7.53 

7.78 

8.03 

8.28 

8.53 

8.79 

9.04 

J.29 

J.54 

9.80 

10.05 

5.1 

5.2 

7.55 

7.80 

8.05 

8.^0 

8.55 

8.81 

9.06 

9.31 

J.56 

9.82 

10.07 

5.2 

5.3 

7.57 

7.82 

8.07 

8.32 

S.57 

8.83 

9.08 

9.33 

J.58 

9.84 

10.09 

5.3 

5.4 

7.59 

7.84 

8.09 

8.34 

8.60 

8.85 

9.10 

J.36 

9.61 

9.86 

10.11 

5.4 

5.5 

7  61 

7  86 

8  11 

8  36 

S  69 

8  87 

9  19 

9  SS 

9  68 

0  PS 

10  13 

5  5 

5.6 

7.63 

7.88 

3.13 

8.39 

8.64 

8.89 

J.15 

9.40 

9.65 

9.90 

10.15 

5.6 

5.7 

7.65 

7.90 

8.15 

8.41 

8.66 

8.91 

.17 

9.42 

9.67 

9.92 

0.17 

5  .  7 

5.8 

7.67 

7.92 

8.17 

8.43 

8.68 

8.94 

9.19 

9.44 

9.61) 

9.94 

0.19 

58 

5.9 

7.69 

7.94 

3.20 

8.45 

3.70 

8.96 

J.21 

J.46 

9.71 

9.96 

10.22 

5.9 

6.0 

7.71 

7.96 

8.22 

8.47 

B.72 

8.98 

9  2-°> 

9.48 

9.73 

D.98 

10.2* 

6.0 

262  Testing  Milk  and  Its  Products. 

Directions  for  Use  of  Tables  VII,  VIII,  IX,  and  XI. 

TABLES  VII,  and  VIII.  Find  the  test  of  the  milk  in  table  VII  or 
of  cream  in  table  VIII;  the  first  or  last  horizontal  row  of  fig- 
ures, the  amounts  of  fat  in  ten  thousand,  thousands,  hundreds, 
tens,  and  units  of  pounds  of  milk  are  then  given  in  this  verti- 
cal column.  By  adding  the  corresponding  figures  for  any  given 
quantity  of  milk  or  of  cream,  the  total  quantity  of  butter  fat 
contained  therein  is  obtained. 

Example:  How  many  pounds  of  fat  is  contained  in  8925  Ibs.  of  milk 
testing  3.«5  per  cent.?  On  p.  264,  second  column  the  test  3.65  is  round,  and 
by  going  downward  in  this  coiumn  we  Lave: 

80CO  Ibs 292.     Ibs. 

900  Ib.s 32.9  Ibs. 

20  Ibs 7  Ibs. 

5  Ibs 2  ibs. 

8925  Ibs.  of  milk.  32 3. 8  Ibs.  of  fat. 

8925  Ibs.  of  milk  testing  3.65  per  cent.,  therefore,  contains  325.8  Ibs.  of 
butter  fat. 

TABLC  IX.  The  price  per  pound  is  given  in  the  outside  vertical 
columns,  and  the  weight  of  butter  fat  in  the  upper  and  lower 
horizontal  row  of  figures.  The  corresponding  tens  of  pounds 
are  found  by  moving  the  decimal  point  one  place  to  the  left, 
the  units,  by  moving  it  two,  and  the  tenths  of  a  pound,  by 
moving  it  three  places  to  the  left.  The  use  of  tho  table  is, 
otherwise,  as  explained  above. 

Example:    How  much  money  is  due  for  325.8  Ibs.  of  butter  fnt  at  1 
p.  247>* 


cents  per  pound?    In  the  horizontal  row  of  figures  beginning  with  lo%  ou 
~^ find: 


800      Ibs $40.50 

20      Ibs 3.10 

6      Ibs 77 

.8  Ibs 12 


325.8  Ibs.  $50.49 

826.8  Ibs.  of  butter  fat  at  15%  cents  per  pound,  therefore,  Is  worth  $50.49. 

TABLE  XI.  Find  the  test  of  milk  in  the  upper  or  lower  hori- 
zontal row  of  figures.  The  amounts  of  butter  likely  to  be  made 
from  ten  thousand,  thousands,  hundreds,  tens,  and  units  of 
pounds  of  milk  are  then  given  in  this  vertical  column.  The  use 
of  the  table  is,  otherwise,  as  explained  above  in  case  of  table  VII. 

Example:  How  much  butter  will  5845  Ibs.  of  milk  testing  3.8  per  cent, 
be  apt  to  make  under  good  creamery  conditions?  In  the  column  headed 
3.8,  we  find : 

6000  Ibs 209.0  Ibs. 

800  Ibs 33.4  Ibs. 

40  Ibs 1.7  Ibs. 

6  Ibs 2  Ibs. 


6845  Ibs.  244.3  Ibs. 

5815  Ibs.  of  milk  test  ng  3.8  per  cent,  of  fat  will  make  about  244.3  lb§.  of 
butter,  ui»il(M-  conditions  similar  to  those  explained  on  pp.  J%-7. 


Appendix. 


263 


Table  VII.     Pounds  of  fat  in  I  to  10,000  Ibs.  of  miik,  testing  3.0 
to  5.35  per  cent.     (See  directions  for  use,  p.  262.) 


I 

3.00 

3.05 

3.10 

3.15 

3.20 

3.25 

3.30 

3.35 

3.40 

3.45 

3.50 

3.55 

j( 

Milk 

Milk 

Ibs. 

Ibs. 

10,000 

300 

305 

310 

315 

320 

325 

330 

335 

340 

345 

350 

355 

10,000 

9,000 

270 

275 

279 

284 

289 

293 

297 

302 

306 

311 

315 

320 

9,000 

8,000 

240 

244 

248 

252 

256 

260 

264 

268 

272 

276 

280 

284 

8,000 

7,000 

210 

214 

217 

221 

224 

228 

231 

235 

238 

242 

245 

249 

7,000 

6,000 

ISO 

183 

186 

189 

-192 

195 

198 

201 

204 

207 

210 

213 

6,000 

5,000 

150 

153 

155 

158 

160 

163 

165 

168 

170 

173 

175 

178 

5,000 

4,000 

120 

122 

124 

126 

128 

130 

132 

134 

136 

138 

140 

142 

4,000 

3,000 

90.0 

91.5 

93.0 

94.5 

96.0 

97.5 

99.0 

101 

102 

104 

105 

107 

3,000 

2,000 

60.0 

61.0 

62.0 

63.0 

64.0 

65.0 

66.0 

67.0 

68.0 

69.0 

70.0 

71.0 

2,000 

1,000 

30.0 

30.5 

31.0 

31.5 

32.0 

32.5 

33.0 

33.5 

34.0 

34.5 

35.0 

35.5 

1,000 

900 

27.0 

27.5 

27.9 

28.4 

28.8 

29.3 

29.7 

30.2 

30.6 

31.1 

31.5 

32.0 

900 

800 

24.0 

24.4 

24.8 

25.2 

25.7 

26.0 

26.4 

26.8 

27.2 

27.6 

28.0 

28.4 

800 

700 

21  0 

9-|  /| 

91  7 

•>9  1 

99  4 

9-?  8 

<>3  1 

93  5 

93  8 

94  9 

94  5 

94  9 

700 

600 

18.0 

18.3 

18.6 

18.9 

19.2 

19.5 

19.8 

20.1 

20.4 

20.7 

21.0 

21.3 

600 

500 

15.0 

15.3 

15.5 

15.8 

10.0 

16.3 

16.5 

16.8 

17.0 

17.3 

17.5 

17.8 

500 

400 

12.0 

12.2 

12.4 

12.6 

12.8 

13.0 

13.2 

13.4 

13.6 

13.8 

14.0 

14.2 

400 

300 

9.0 

9.2 

9.3 

9.5 

9.6 

9.8 

9.9 

10.1 

10.2 

10.4 

10.5 

10.7 

300 

200 

6.0 

6.1 

6.2 

6.3 

6.4 

6.5 

6.6 

6.7 

6.8 

6.9 

7.0 

7.1 

200 

100 

3  0 

3  1 

3  1 

3  9 

3  9 

3  3 

3  3 

3  4 

3  4 

3  5 

3  5 

36 

100 

90 

2.7 

2.8 

2.8 

2.8 

2.9 

2.9 

3.0 

3.0 

3.1 

3.1 

3.2 

3.2 

90 

80 

2.4 

2.4 

2.5 

2.5 

2.6 

2.6 

2.6 

2.7 

2.7 

2.8 

2.8 

2.8 

80 

70 

2J 

2.1 

2.2 

2.2 

2.2 

2.3 

2.3 

2.3 

2.4 

2.4 

2.5 

2.5 

70 

60 

1.8 

1,8 

1.9 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

2.1 

60 

50 

1  5 

1  5 

1  6 

1  6 

1  6 

1  6 

1  7 

1  7 

1  7 

1  7 

1  8 

1  8 

50 

40 

1.2 

1.2 

1.2 

1.3 

1.3 

1.3 

1.3 

1.3 

1.4 

1.4 

1.4 

1.4 

40 

30 

.9 

.9 

.9 

.9 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

30 

20 

.6 

.6 

.6 

.6 

.6 

.7 

.7 

.7 

.7 

.7 

.7 

.7 

20 

10 

3 

3 

.31  -3 

3 

3 

3 

3 

3 

3 

4 

4 

10 

9 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

9 

8 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

8 

7 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

7 

6 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

6 

5 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

4 

3 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

3 

•  2 

.1 

.1 

.1 

.1 

.1 

1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

1 

3.45 

1 

3.00 

3.05 

3.10 

3.15 

3.20 

3.25 

3.30 

3.35 

3.40 

3.50 

3.55 

i 
* 

H 

264  Testing  Milk  and  Its  Products. 

Table  VH.    Pounds  of  fat  in  I  to  10,000  Ibs.  of  milk  ( Continued). 


i 

1 

3.60 

3.65 

3.70 

3.75 

3.80 

3.85 

3.90 

3.95 

4.00 

4.05 

4.10 

4.15 

? 

Milk 

Milk 

Ibs. 

Ibs. 

10,000 

360 

365 

370 

375 

380 

385 

390 

395 

400 

405 

410 

415 

10,000 

9,000 

324 

329 

333 

338 

342 

347 

351 

356 

360 

365 

369 

374 

9,000 

8,000 

288 

292 

296 

300 

304 

308 

312 

316 

320 

324 

328 

332 

8,000 

7.000 

252 

256 

259 

263 

266 

270 

273 

277 

280 

284 

287 

291 

7,000 

6,000 

216 

219 

222 

225 

228 

231 

234 

237 

240 

243 

246 

249 

6,000 

5,000 

180 

183 

185 

188 

190 

193 

195 

198 

200 

203 

205 

208 

5,000 

4,000 

!  144 

146 

148 

150 

152 

154 

156 

158 

160 

162 

164 

166 

4,000 

3,000 

108 

110 

111 

113 

114 

116 

117 

119 

120 

122 

123 

125 

3,000 

2,000 

72.0 

73.0 

74.0 

75.0 

76.0 

77.0 

78.0 

79.0 

80.0 

81.0 

82.0 

83.0 

2,000 

1,000 

36.0 

36.5 

37.0 

37.5 

38.0 

38.5 

39.0 

39.5 

40.0 

40.5 

41.0 

41.5 

1,000 

900 

32.4 

32.9 

33.3 

33.8 

34.2 

34.7 

35.1 

35.6 

36.0 

36.5 

36.9 

37.4 

900 

800 

28.8 

29.2 

29.6 

30.0 

30.4 

30.8 

31.2 

31.6 

32.0 

32.4 

32.8 

33.2 

800 

700 

25.2 

25.6 

25.9 

26.3 

26.6 

27.0 

27.3 

27.7 

28.0 

28.4 

28.7 

29.1 

700 

600 

21.6 

21.9 

22.2 

22.5 

22.  S 

23.1 

23.4 

23.7 

24.0 

24.3 

24.6 

24.9 

600 

500 

18.0 

18.3 

18.5 

18.8 

19.0 

19.3 

19.5 

19.8 

20.0 

20.3 

20.5 

20.8 

500 

400 

14.4 

14.6 

14.8 

15.0 

15.2 

15.4 

15.6 

15.8 

16.0 

16.2 

16.4 

16.6 

400 

300 

10.8 

11.0 

11.1 

11.3 

11.4 

11.6 

11.7 

11.9 

12.0 

12.2 

12.  ij 

12.5 

300 

200 

7.2 

7.3 

7.4 

7.5 

7.6 

7.7 

7.8 

7.9 

8.0 

8.1 

8.2 

8.3 

200 

100 

3.6 

3.7 

3.7 

3.8 

3.8 

3.9 

3.9 

4.0 

4.0 

4.1 

4.1 

4.2 

100 

90 

3  9 

3  3 

3  3 

34 

3  4 

3  5 

3  5 

3  6 

3  6 

3  7 

3  7 

3  7 

90 

80 

2.9 

2.9 

3.0 

3.0 

3.0 

3.1 

3.1 

3.2 

3.2 

3.2 

3.3 

3.3 

80 

70 

2.5 

2.6 

2.6 

2.6 

2.7 

2.7 

2.7 

2.8 

2.8 

2.8 

2.9 

2.9 

70 

60 

2  9 

9  9 

9  9 

9  3 

9  3 

9  3 

9  3 

9  4 

9  4 

?  4 

9  5 

9  5 

60 

50 

1.8 

1.8 

1.9 

1.9 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

50 

40 

Ofi 

1.4 

1.5 

1.5 

1.5 

1.5 

1.5 

Tn 

1.6 

19 

1.6 

19 

1.6 

1  9 

1.6 

19 

1.6 

19 

1.7 

19 

40 

on 

oU 

20 

7 

7 

7 

8 

8 

.  Z 

8 

.Z 

8 

.Z 

8 

1  Z 

8 

.Z 

8 

.Z 

s 

.Z 

8 

OU 

20 

10 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

10 

9 

3 

3 

3 

3 

3 

3 

4 

4 

4 

4 

4 

4 

9 

8 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

8 

7 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

7 

0 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

6 

5 

.2 

.2 

.2 

.2 

.2 

.^ 

.2 

.2 

.2 

.2 

.2 

.2 

5 

4 

.1 

.1 

.1 

.2 

.2 

'2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

3 

2 

.1 

.1 

.1 

.1 

i 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

1 

1 

3.60 

3.65 

3.70 

3.75 

3.80 

3.85 

3.90 

5.95 

4.00 

4.05 

4.10 

4.15 

jl 

Appendix. 


265 


Table  VII.    Pounds  of  fat  in  I  to  10,000  Ibs.  of  milk  (Continued). 


i 
§ 

4.20 

4.25 

4.30 

4.35 

4.40 

440 
396 
352 
308 
264 
220 
176 
132 
88.0 
44.0 

39  6 

4.45 

4.50 

4.55 

4.60 

4.65 

4.70 

4.75 

I 

Milk 
Ibs. 

10,000 
9,000 
8,000 
7,000 
6,000 
5,000 
4,000 
3,000 
2,000 
1,000 

900 
800 
700 
600 
500 
400 
300 
200 
100 

90 
80 
70 
60 
50 
40 
30 
20 
10 

9 
8 
7 
6 
5 
4 
3 
2 
1 

420 
378 
336 
294 
252 
210 
168 
126 
84.0 
42.0 

37.8 
33.6 
29.4 
25.2 
21.0 
16.8 
12.6 
8  4 

425 

383 
340 
298 
255 
213 
170 
128 
85.0 
42.5 

3S  3 

430 
387 
344 
301 
258 
215 
172 
129 
86.0 
43.0 

38  7 

435 
392 
348 
305 
261 
218 
174 
131 
87.0 
43.5 

39  9 

445 
401 
356 
312 
267 
223 
178 
134 
89.0 
44.5 

40  1 

450 
405 
360 
315 
270 
225 
180 
135 
90.0 
45.0 

40  5 

455 
410 
364 
319 
273 
228 
182 
137 
91.0 
45.5 

41  0 

460 
414 
368 
322 
276 
230 
184 
138 
92.0 
46.0 

41  4 

465 
419 
372 
326 
279 
233 
186 
140 
93.0 
46.5 

41  9 

470 
423 
376 
329 
282 
235 
188 
141 
94.0 
47.0 

4ft  8 

475 
428 
380 
333 
285 
238 
190 
143 
95.0 
47.5 

4ft  8 

Milk 
Ibs. 

10,000 
9,000 
8,000 
7,000 
6,000 
5,OCO 
4,000 
3,000 
2,000 
1,000 

900 
800 
700 
600 
500 
400 
300 
200 
100 

90 
80 
70 
60 
50 
40 
30 
20 
10 

9 
8 
7 
6 
5 
4 
3 
2 
1 

31.0 
29.8 
25.5 
21.3 
17.0 
12.8 
8  5 

34.4 
30.1 
"5.8 
21.5 
17.2 
12.9 
8  fi 

34.8 
30.5 
26.1 
21.8 
17.4 
13.1 
8  7 

35.2 

30.8 
26.4 
22.0 
17.6 
13.2 
8  8 

35.6 
31.2 
26.7 
22.3 
17.8 
13.4 
8  9 

36.0 
31.5 
27.0 
22.5 
18.0 
13.5 
9  0 

36.4 
31.9 
27.3 

22.8 
18.2 
13.7 
9  1 

36.8 
32.2 
27.6 
23.0 
18.4 
13.8 
9  ft 

37.2 
32.6 
27.9 
23.3 
18.6 
14.0 
9  3 

37.6 
32.9 
28.2 
23.5 
18.8 
14.1 
9  4 

38.0 
33.3 
28.5 
23.8 
19.0 
14.3 
9  5 

4.2 
3  8 

4.3 

3  8 

4.3 
8  9 

4.4 

3  9 

4.4 
4  0 

4.5 
4  0 

4.5 
4  1 

4.6 
4  1 

4.6 
4  1 

4.7 
4  ft 

4.7 
4  ft 

4.8 
4  3 

3  4 

3  4 

8  4 

8  5 

8  5 

3  6 

3  6 

3  f> 

3  7 

3  7 

8  8 

8  8 

ft  9 

3  0 

8  0 

8  0 

8  1 

8  1 

3  ft 

3  ft 

3  ft 

3  8 

8  8 

3  3 

ft  5 

ft  fi 

9,  6 

ft  B 

ft  6 

ft  7 

ft  7 

ft  7 

ft  8 

ft  8 

ft  8 

ft  9 

9,  1 

ft  1 

ft  ft 

ft  ft 

ft  ft 

ft  ft 

ft  3 

ft  8 

ft  3 

ft  3 

ft  4 

ft  4 

1.7 
1  3 

1.7 
1  3 

1.7 
1  3 

1.7 
1   3 

1.8 
1  3 

1.8 
1  8 

1.8 
1  4 

1.8 
1  4 

1.8 
1  4 

1.9 
1  4 

1.9 
1  4 

1.9 
1  4 

8 

9 

q 

q 

q 

q 

q 

q 

q 

q 

q 

1  0 

4 

4 

4 

4 

4 

4 

6 

5 

5 

5 

5 

6 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

.3 
3 

.3 
8 

.3 
3 

.3 
8 

.4 
3 

.4 
3 

.4 
8 

.4 
3 

.4 
3 

.4 
3 

.4 
3 

.4 
8 

8 

3 

8 

8 

3 

3 

3 

3 

3 

3 

3 

.2 
2 

.2 
2 

.2 
2 

.2 
ft 

.2 

ft 

.2 
ft 

.2 
2 

.2 
ft 

.2 
ft 

.2 

ft 

.2 
ft 

.2 

ft 

.1 
1 

.1 
1 

.1 
1 

.1 
1 

.1 
1 

.1 
1 

.1 

1 

.1 

1 

.1 
1 

.1 

1 

.1 
1 

.1 
1 

t: 

4  90 

4  9,5 

4  30 

4  35 

4  40 

4  45 

4  50 

4  55 

4  60 

4  65 

4  70 

4  75 

H 

O> 

cc 

266  Testing  Milk  and  Its  Products. 

Table  VII.    Pounds  of  fat  in  I  to  10,000  Ibs.  of  milk  ( Continued). 


I 

4.80 

4.85 

4.90 

4.95 

5.00 

5.05 

5.  10 

5.15 

5.20 

5.25 

5.30 

5.35 

I 

Milk 

Milk 

Ibs. 

Ibs. 

10,000 

480 

485 

490 

495 

500 

505 

510 

515 

520 

525 

530 

535 

10,000 

9,000 

432 

437 

441 

446 

450 

455 

459 

464 

468 

473 

477 

482 

9^000 

8,000 

384 

388 

392 

396 

400 

404 

408 

412 

416 

420 

424 

428 

8,000 

7,000 

336 

340 

343 

347 

350 

354 

357 

361 

364 

368 

371 

375 

7,000 

6,000 

288 

291 

294 

297 

300 

303 

306 

309 

312 

315 

318 

321 

6,000 

5,000 

240 

243 

245 

248 

250 

253 

255 

258 

260 

263 

265 

268 

5,000 

4,000 

192 

194 

196 

198 

200 

202 

204 

206 

208 

210 

212 

214 

4,000 

3,000 

144 

146 

147 

149 

150 

152 

153 

155 

156 

158 

159 

161 

3,000 

'2,000 

96.0 

97.0 

98.0 

99.0 

100 

101 

102 

103 

104 

105 

106 

107 

2,000 

1,000 

48.0 

48.5 

49.0 

49.5 

50.0 

50.5 

51.0 

51.5 

52.0 

52.5 

53.0 

53.5 

1,000 

900 

43.2 

43.7 

44.1 

44.6 

45.0 

45.5 

45.7 

46.4 

46.8 

47.3 

47.7 

48.2 

900 

800 

38.4 

38.8 

39.2 

39.6 

40.0 

40.4 

40.8 

41.2 

41.6 

42.0 

42.4 

42.8 

800 

700 

33.6 

34.0 

34.3 

34.7 

35.0 

35.4 

35.7 

36.1 

36.4 

36.8 

37.1 

37.5 

700 

600 

28.8 

29.1 

29.4 

29.7 

30.0 

30.3 

30.6 

30.9 

31.2 

31.5 

31.8 

32.1 

600 

500 

24.0 

24.3 

24.5 

24.8 

25.0 

25.3 

25.5 

25.8 

26.0 

26.3 

26.5 

26.8 

500 

400 

19.2 

19.4 

19.6 

19.8 

20.0 

20.2 

20.4 

20.6 

20.8 

21.0 

21.2 

21.4 

400 

300 

14.4 

14.6 

14.7 

14.9 

15.0 

15.2 

15.3 

15.5 

15.6 

15.8 

15.9 

16.1 

300 

200 

9.6 

9.7 

9.8 

9.9 

10.0 

10.1 

10.2 

10.3 

10.4 

10.5 

10.6 

10.7 

200 

100 

4.8 

4.9 

4.9 

5.0 

5.0 

5.1 

5.1 

5.2 

5.2 

5.3 

5.3 

5.4 

100 

90 

4.3 

4.4 

4.4 

4.5 

4.5 

4.5 

4.6 

4.6 

4.7 

4.7 

4.8 

4.8 

90 

80 

3.8 

3.9 

3.9 

4.0 

4.0 

4.0 

4.1 

4.1 

4.2 

4.2 

4.2 

4.3 

80 

70 

3.4 

3.4 

3.4 

3.5 

3.5 

3.5 

3.6 

3.6 

3.6 

3.7 

3.7 

3.7 

70 

60 

2.9 

2.9 

2.9 

3.0 

3.0 

3.0 

3.1 

3.1 

3.1 

3.2 

3.2 

3.2 

60 

50 

2.4 

2.4 

2.5 

2.5 

2.5 

2.5 

2.6 

2.6 

2.6 

2.6 

2.7 

2.7 

50 

40 

1.9 

1.9 

2.0 

2.0 

2.0 

2.0 

2.0 

2.1 

2.1 

2.1 

2.1 

2.1 

40 

30 

1.4 

1.5 

1.5 

1.5 

1.5 

1.5 

1.5 

1.5 

1.6 

1.6 

1.6 

1.6 

30 

20 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.1 

1.1 

1.1 

20 

10 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

10 

9 

.4 

.4 

.4 

.4 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

9 

8 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

4 

8 

7 

.3 

.3 

.3 

.3 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

.4 

7 

6 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

G 

5 

.2 

.2 

.2 

.2 

.3 

.3 

.b 

.3 

.3 

.3 

.3 

.3 

5 

4 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

3 

.1 

.1 

.1 

.1 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

3 

P 

2 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

'.1 

2 

1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

1 

4.95 

5.00 

5.20 

5.25 

1 

4.80 

4.85 

4.90 

5.05 

5.10 

5.15 

5.30 

5.35 

5 

H 

r 

Appendix. 


267 


Table  VIII.     Pounds  of  fat  in  I  to  1000  Ibs.  of  cream  testing 
12.0  to  50.0  per  cent.  fat. 

(See  directions  for  use,  p.  262) 


I 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

K 

1000 

120 

180 

140 

150 

160 

170 

180 

190 

200 

210 

220 

230 

240 

250 

260 

270 

280 

290 

300 

900 

108 

117 

126 

135 

144 

153 

162 

171 

180 

18-' 

198 

207 

216 

225 

284 

243 

252 

261 

270 

800 

96 

104 

112 

120 

128 

136 

144 

152 

160 

168 

176 

184 

192 

200 

208 

216 

224 

232 

24J 

700 

84 

91 

98 

105 

112 

119 

126 

133 

no 

147 

151 

161 

163 

175 

182 

189 

196 

k03 

210 

600 

72 

78 

84 

90 

96 

102 

108 

114 

120 

126 

132 

138 

144 

150 

156 

162 

168 

174 

180 

500 

60 

65 

70 

75 

80 

85 

90 

95 

100 

105 

110 

115 

120 

125 

130 

135 

140 

145 

150 

400 

48 

52 

56 

60 

64 

68 

72 

76 

80 

84 

88 

92 

96 

100 

104 

108 

112 

116 

120 

800 

36 

39 

42 

45 

48 

51 

54 

57 

60 

63 

66 

69 

72 

75 

78 

81 

84 

87 

90 

200 

24 

26 

28 

30 

32 

34 

36 

38 

40 

42 

44 

4H 

48 

50 

52 

54 

5<> 

68 

60 

100 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

90 

10.8 

11.7 

12.6 

13.5 

14.4 

15.3 

16.2 

17.1 

18.0 

18.9 

19.8 

20.7 

21.6 

22.5 

23.4 

24.3 

25.2 

26.1 

27.0 

80 

9.6 

10.4 

11.2 

12.0 

12.8 

13.6 

14.4 

15.2 

16.0 

16.8 

17.6 

18.4 

19.2 

0.0 

20.8 

21.6 

22.4 

23.2 

24.0 

70 

8.4 

9.1 

9.8 

10.5 

11.2 

11.9 

12.6 

13.8 

14.0 

14.7 

15.4 

16.1 

16.8 

17.5 

18.2 

18.9 

19.6 

20..3 

21.0 

60 

7.2 

7.8 

8.4 

9.0 

9.6 

10.2 

10.8 

11.4 

12.0 

12.6 

13.2 

13.8 

14.4 

15.0 

15.6 

16.2 

16.8 

17.4 

18.0 

50 

6.0 

6.5 

7.0 

7.5 

8.0 

8.5 

9.0 

9.5 

10.0 

10.5 

11.0 

11.5 

12.0 

12.5 

13.0 

13.5 

14.0 

4.5 

15.0 

40 

4.8 

5.2 

5.6 

6.0 

6.4 

6.8 

7.2 

7.6 

8.0 

8.4 

8.8 

9.2 

9.6 

10.0 

10.4 

10.8 

11.2 

11.6 

12.0 

30 

3.6 

3.9 

4.2 

4.5 

4.8 

5.1 

5.4 

5.7 

6.0 

6.3 

6.6 

6.9 

7.2 

7.5 

7.8 

8.1 

8.4 

8.7 

9.0 

20 

2.4 

2.6 

2.8 

3.0 

3.2 

3.4 

3.6 

3.8 

4.0 

4.2 

4.4 

4.6 

4.8 

5.0 

5.2 

5.4 

5.6 

5.8 

6.0 

10 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

1.8 

1.9 

2.0 

2.1 

2.2 

2.8 

2.4 

2.5 

2.6 

2.7 

2.8 

2.9 

3.0 

0 

1.08 

1.17 

1.26 

1.85 

1.44 

I.  S3 

1.62 

1.71 

1.80 

1.89 

1.98 

2.07 

2.16 

2.25 

2.34 

1.43 

2.52 

2.61 

2.70 

8 

.96 

1.04 

1.12 

1.20 

1.28 

1.36 

1.44 

1.52 

1.60 

1.68 

1.76 

1.84 

1.92 

2.00 

2.08 

2.16 

2.24 

2.32 

2.40 

7 

.84 

.91 

.9>S 

1.05 

1.12 

1.19 

1.26 

1.33 

1.40 

1.47 

1.54 

1.61 

l.«8 

1.75 

1.82 

1.89 

1.96 

2.03 

2.10 

6 

.72 

.78 

.84 

.90 

.% 

1.02 

1.08 

1.14 

1.20 

1.26 

1.32 

1.38 

1.44 

1.50 

1.56 

1.62 

1.68 

1.74 

1.80 

5 

.60 

.65 

.70 

.75 

.80 

.85 

.90 

.95 

1.00 

l.Oo 

1.10 

1.15 

1.20 

1.25 

1.30 

1.85 

1.40 

1.45 

1.50 

4 

.48 

.52 

.56 

.60 

.64 

.68 

.72 

.76 

.80 

.84 

.88 

.92 

.91. 

1.00 

1.04 

1.08 

1.12 

1.16 

1.20 

3 

.36 

.39 

.42 

.45 

.48 

.51 

.54 

.57 

.60 

.63 

.66 

.69 

.72 

.75 

.78 

.81 

.84 

.87 

.90 

2 

.24 

.26 

.28 

.30 

.32 

.34 

.36 

.38 

.40 

.42 

.44 

.46 

.48 

.50 

.52 

.54 

.51) 

.58 

.60 

1 

.12 

.13 

.14 

.15 

.16 

.17 

.18 

.19 

.20 

.21 

.22 

.23 

.24 

.25 

.26 

.27 

.28 

.29 

.30 

268 


Testing  Milk  and  Its  Products. 


Table  Mil.     Pounds  of  fat  in  I  to  1000  Ibs.  of  cream  (continued). 


I 

81 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

60 

11 

1000 

310 

320 

380 

340 

350 

360 

370 

380 

390 

400 

410 

420 

430 

440 

450 

460 

470 

480 

490 

500 

900 

279 

288 

297 

306 

315 

324 

833 

342 

351 

360 

369 

378 

387 

896 

405 

414 

423 

482 

441 

450 

800 

248 

256 

264 

272 

280 

288 

296 

304 

312 

820 

328 

336 

844 

352 

360 

368 

376 

384 

892 

400 

700 

217 

224 

231 

238 

245 

252 

259 

266 

273 

280 

287 

294 

301 

308 

815 

322 

829 

386 

843 

850 

600 

186 

192 

198 

204 

210 

216 

222 

228 

234 

240 

246 

252 

258 

264 

270 

276 

282 

288 

294 

800 

500 

155 

160 

165 

170 

175 

180 

18) 

190 

195 

200 

205 

210 

215 

2-20 

225 

280 

235 

240 

245 

250 

400 

124 

128 

132 

136 

140 

144 

148 

152 

156 

160 

164 

168 

172 

176 

180 

184 

188 

192 

196 

200 

800 

93 

96 

99 

102 

105 

108 

111 

114 

117 

120 

123 

126 

129 

132 

135 

188 

141 

144 

147 

150 

200 

62 

64 

66 

68 

70 

72 

74 

76 

78 

80 

82 

84 

86 

88 

90 

92 

94 

96 

98 

100 

100 

81 

82 

33 

34 

85 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

90 

27.9 

28.8 

29.7 

30.6 

31.5 

82.4 

33.3 

84.2 

35.1 

86.0 

36.9 

37.8 

38.7 

39.6 

40.5 

41.4 

42.3 

43.2 

44.1 

45.0 

80 

24.8 

25.6 

26.4 

27.2 

28.0 

28.8 

29.6 

30.4 

21.2 

32.0 

32.8 

33.6 

34.4 

35.2 

36.036.8 

37.  6188.4 

39.2 

40.0 

70 

21.7 

22.4 

23.1 

23.8 

24.5 

25.2 

25.9 

26.6 

27.8 

28.0 

28.7 

29.4 

30.1 

30.8 

31.5:32.2 

32.988.6 

34.8 

35.0 

60 

18.6 

19.2 

19.8 

20.4 

21.0 

21.6 

22.2 

22.8 

28.4 

24.0 

24.6 

25.2 

25.8 

26.4 

27.027.6 

28.2:28.8 

29.4(80.0 

60 

15.5 

16.0 

16.5 

17.0 

17.5 

18.0 

18.5 

19.0 

19.5 

20.0 

20.5 

21.0 

21.5 

22.0 

22.523.0 

28.524.0 

24.5 

25.0 

40 

12.4 

12.8 

13.2 

13.6 

14.0 

14.4 

14.8 

15.2 

15.6 

16.0 

16.4 

16.8 

17.2 

17.6 

18.0  18.4 

18.8 

19.2 

19.6 

20.0 

80 

9.8 

9.6 

9.9 

10.2 

10.5 

10.8 

11.1 

11.4 

11.7 

12.0 

12.3 

12.6 

12.9 

18.2 

18.518.8 

14.1 

14.4 

14.7 

15.0 

20 

8.2 

6.4 

6.6 

6.8 

7.0 

7.2 

7.4 

7.6 

7.8 

8.0 

8.2 

8.4 

8.6 

8.8 

9.0  9.2 

9.4 

9.6 

9.8 

10.0 

10 

8.1 

8.2 

8.8 

3.4 

8.5 

8.6 

8.7 

3.8 

3.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5  4.6 

4.7 

4.8 

4.9 

5.0 

9 

2.79 

2.88 

2.97 

8.06 

8.15 

3.24 

3.38 

3.42 

3.51 

3.60 

3.69 

8.78 

3.87 

8.964.9514.14 

4.28 

4.82 

4.41 

4.50 

8 

2.48 

2.56 

2.64 

2.72 

2.80 

2.88 

2.96 

3.04 

3.12 

3.20 

8.28 

8.363.44 

3.52 

3.603.68 

3.763.84 

3.924.00 

7 

2.17 

2.24 

2.81 

2.38 

2.45 

2.52 

2.59 

2.66 

2.73 

2.80 

2.87 

2.943.01 

3.08 

8.15:8.22 

3.29 

3.86 

3.43 

3.50 

6 

1.8ft 

1.92 

1.98 

2.04 

2.10 

2.16 

2.22 

2.28 

2.34 

2.40 

2.46 

2.522.58 

2,64 

2.702.76 

2.82 

2.88 

2.94 

3.00 

5 

1.56 

1.60 

1.65 

1.70 

1.75 

1.80 

1.85 

1.90 

1.95 

2.00 

2.0-5 

2.102.15 

2.20 

2.252.30 

2.85 

2.40 

2.45 

2.60 

4 

1.24 

1.28 

1.82 

1.36 

1.40 

1.44 

1.48 

1.52 

1.56 

1.60 

1.64 

1.681.72 

1.76 

1.80 

1.84 

1.88 

1.92 

1.06 

2.00 

8 

.93 

.96 

.99 

1.02 

l.Oo 

1.08 

1.11 

1.14 

1.17 

1.20 

1.23 

1.26,1.29 

1.82 

1.35 

1.38 

1.41 

1.44 

l.*7 

1.60 

a 

.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

.82 

.81 

.86 

.88 

.90  .92 

.94 

.96 

.98 

1.00 

i 

.81 

.82 

.38 

.34 

.35 

.£6 

.87 

.38 

.39 

.40 

.41 

.42 

.43 

.44 

.45  .46 

.47 

.48 

.49 

.60 

Appendix. 


269 


Table    IX.     Amount  due  for  butter  fat,  in  dollars  and  cents,  at 
12  to  25  cents  per  pound. 

(See  directions  for  use,  page  262.) 


ss 

!j 

12 

12} 

12} 

12} 

Pounds  of  butter  fat. 

p-o 

p 

w 

12 
12} 
12} 
12} 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

$ 

120.00 
122.50 
125.00 
127.50 

$ 

108.00 
110.25 
112.50 
114.75 

$ 

96.00 
98.00 
100.00 
102.00 

$ 

84.00 
85.75 
87.50 
89.25 

72.00 
73.50 
75.00 
76.50 

$ 

60.00 
61.25 
62.50 
63.75 

$ 

48.00 
49.00 
50.00 
51.00 

36.00 
36.75 
37.50 
38.25 

$ 

24.00 
24.50 
25.00 
25.50 

$ 

12.00 
12.25 
12.50 
12.75 

13 

13} 

13} 

130.00 
132.50 
135.00 
137.50 

117.00 
119.25 
121.50 
123.75 

104.00 
106.00 
108.00 
110.00 

91.00 
92.75 
94.50 
96.25 

78.00 
79.50 
81.00 
82.50 

65.00 
66.25 
67.50 
68.75 

52.00 
53.00 
54.00 
55.00 

39.00 
39.75 
40.50 
41.25 

26.00 
26.50 
27.00 
27.50 

13.00 
13.25 
13.50 
13.75 

13 
13} 
13} 
13} 

14 
14} 

140.00 
142.50 
145.00 
147.50 

126.00 
128.25 
130.50 
132.75 

112.00 
114.00 
116.00 
118.00 

98.00 
99.75 
101.50 
103.25 

84.00 
85.50 
87.00 
88.50 

70.00 
71.25 
72.50 
73.75 

56.00 
57.00 
58.00 
59.00 

42.00 
42.75 
43.50 
44.25 

28.00 
28.50 
29.00 
29.50 

14.00 
14.25 
14.50 
14.75 

14 
14} 
14} 
14} 

15 
15} 

150.00 
152.50 
155.00 
157.50 

135.00 
137.25 
139.50 
141.75 

120.00 
122.00 
124.00 
126.00 

105.00 
106.75 
108.50 
110.25 

90.00 
91.50 
93.00 
94.50 

75.00 
76.25 
77.50 
78.75 

60.00 
61.00 
62.00 
63.00 

45.00 
45.75 
46.50 
47.25 

30.00 
30.50 
31.00 
31.50 

15.00 
15.25 
15.50 
15.75 

15 

15} 
15} 

16 
16} 
16} 
16} 

160.00 
162.50 
165.00 
167.50 

144.00 
146.25 
148.50 
150.75 

128.00 
130.00 
132.00 
134.00 

112.00 
113.75 
115.50 
117.25 

96.00 
97.50 
99.00 
100.50 

80.00 

81.25 
82.50 

83.75 

64.00 
65.00 
66.00 
67.00 

48.00 
48.75 
49.50 
50.25 

32.00 
32.50 
33.00 
33.50 

16.00 
16.25 
16.50 
16.75 

16 
16} 
16} 
16} 

17 

17} 

m 

17} 

170.00 
172.50 
175.00 
177.50 

153.00 
155.25 
157.50 
159.75 

136.00 
138.00 
140.00 
142.00 

119.00 
120.75 
122.50 
124.25 

102.00 
103.50 
105.00 
106.50 

85.00 
86.25 
87.50 
87.75 

68.00 
69.00 
70.00 
71.00 

51.00 
51.75 
52.50 
53.25 

34.00 
34.50 
35.00 
35.50 

17.00 
17.25 
17.50 
17.75 

17 
17} 
17} 
17} 

18 

181 
18} 

180.00 
182.50 
185.00 
187.50 

162.00 
164.25 
166.50 
168.75 

144.00 
146.00 
148.00 
150.00 

126.00 
127.75 
129.50 
131.25 

108.00 
109.50 
111.00 
112.50 

90.00 
91.25 
92.50 
93.75 

72.00 
73.00 
74.00 
75.00 

54.00 
54.75 
55.50 
56.25 

36.00 
36.50 
37.00 
37.50 

18.00 
18.25 
18.50 
18.75 

18 
18} 
18} 
18} 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

270  Testing  Milk  and  Its  Products. 

lable  IX.       Amount  due  for  butter  fat  (Continued). 


1  Price  per  I 
|  pound,  cents.  | 

Pounds  of  butter  fct. 

|| 

!" 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

9 

$ 

$ 

$ 

$ 

$ 

$ 

$ 

$ 

$ 

19 
19] 

19} 

190.00 
192.50 
195.00 
197.50 

171.00 
173.25 
175.50 
177.75 

152.00 
154.00 
156.00 
158.00 

133.00 
134.75 
136.50 
138.25 

114.00 
115.50 
117.00 
118.50 

95.00 
96.25 
97.50 
98.75 

76.00 
77.00 
78.00 
79.00 

57.00 
57.75 
58.50 
59.25 

38.00 
38.50 
39.00 
39.50 

19.00 
19.25 
19.50 
19.75 

19 

19* 
191 

20 
20} 

20} 

200.00 
202.50 
205.00 
207.50 

180.00 
182.25 
184.50 
186.75 

160.00 
162.00 
164.00 
166.00 

140.00 
141.75 
143.50 
145.25 

120.00 
121.50 
123.00 
124.50 

100.00 
101.25 
102.50 
103.75 

80.00 
81.00 
82.00 
83.00 

60.00 
60.75 
61.50 
62.25 

40.00 
40.50 
41.00 
41.50 

20.00 
20.25 
20.50 
20.75 

20 

20* 
201 
20} 

21 
21* 
211 
21} 

210.00 
212.50 
215.00 
217.50 

189.00 
191.25 
193.50 
195.75 

168.00 
170.00 
172.00 
174.00 

147.00 
148.75 
150.50 
152.25 

126.00 
127.50 
129.00 
130.50 

105.00 
106.25 
107.50 
108.75 

84.00 
85.00 
86.00 
87.00 

63.00 
63.75 
64.50 
65.25 

42.00 
42.50 
43.00 
43.50 

21.00 
21.25 
21.50 
21.75 

21 
211 
211 
21} 

22 
22* 

221 
22} 

220.00 
222.50 
225.00 
227.50 

198.00 
200.25 
202.50 
204.75 

176.00 
178.00 
180.00 
182.00 

154.00 
155.75 
157.50 
159.25 

132.00 
133.50 
135.00 
136.50 

110.00 
111.25 
112.50 
113.75 

88.00 
89.00 
90.00 
91.00 

66.00 
66.75 
67.50 
68.25 

44.00 
44.50 
45.00 
45.50 

22.00 
22.25 
22.50 
22.75 

22 

22* 
22* 
22} 

23 
23* 
231 
23} 

230.00 
232.50 
235.00 
237.50 

207.00 
209.25 
211.50 
213.75 

184.00 
186.00 
188.00 
190.00 

161.00 
162.75 
164.50 
166.25 

138.00 
139.50 
141.00 
142.50 

115.00 
116.25 
117.50 
118.75 

92.00 
93.00 
94.00 
95.00 

69.00 
69.75 
70.50 
71.25 

46.00 
46.50 
47.00 
47.50 

23.00 
23.25 
23.50 
23.75 

23 
23* 
231 
23| 

24 
24* 

241 
24| 
25 

240.00 
242.50 
245.00 
247.50 
250.00 

216.00 
218.25 
220.50 
222.75 
225.00 

192.00 
194.00 
196.00 
108.00 
200.00 

168.00 
169.75 
171.50 
173.25 
175.00 

144.00 
145.50 
147.00 
148.50 
150.00 

120.00 
121.25 
122.50 
123.75 
125.00 

96.00 
97.00 
98.00 
99.00 
100.00 

72.00 
72.75 
73.50 
74.25 
75.00 

48.00 
48.50 
49.00 
49.50 
50.00 

24.00 
24.25 
24.50 
24.75 
25.00 

24 

24* 
24^ 
24:1 
25 

1,000 

900 

800 

700 

600 

500 

400 

300 

200 

100 

Appendix. 


271 


Table   X.     Relative-value  tables. 

(See  directions  for  use,  pp.  208-209. 


N 

Price  of  milk  per  100  pounds,  in  dollars  and  cents. 

3  0 

.30 

.31 

88 

.34 

.36 

37 

.39 

40 

4? 

.43 

4o 

3.1 

.31 

.33 

.34 

.36 

.37 

.39 

.40 

.42 

.43 

.45 

3.2 

.32 

.34 

.35 

.37 

.38 

.40 

.42 

.43 

.45 

.46 

.'48 

3  8 

.33 

35 

.36 

.38 

.40 

.41 

.43 

45 

.46 

.48 

49 

3.4 

.34 

.36 

.37 

.39 

.41 

.42 

.44 

.46 

.48 

.49 

.51 

3.5 

.35 

.37 

.38 

.40 

.42 

.44 

.45 

.47 

.49 

.51 

.52 

3.6 

.36  j 

.38 

.40 

.41 

.43 

.45 

.47 

.49 

.50 

.52 

.54 

3.7 

.37 

.39 

.41 

.43 

.44 

.46 

.48 

.50 

.52 

.54 

.55 

3.8 

.38 

.40 

.42 

.44 

.46 

.47 

.49 

.51 

.53 

.55 

.57 

3.9 

.39 

.41 

.43 

.45 

.47 

.49 

.51 

.53 

.55 

.57 

.58 

4  0 

.40 

.42 

44 

.46 

.48 

50 

.52 

54 

.56 

.58 

6C 

4.1 

.41 

.43 

.45 

.47 

.49 

.51 

.53 

.55 

.57 

.59 

.61 

4  a 

.42 

.44 

46 

.48 

.50 

.5-2 

.55 

.57 

.59 

.61 

6«c 

4.3 

.43 

.45 

.47 

.49 

.52 

.54 

.56 

.58 

.60 

.62 

.64 

4  4 

.44 

.46 

48 

.51 

.53 

.55 

.57 

59 

62 

.64 

6C5 

4.5 

.45 

.47 

.49 

.52 

.54 

.56 

.58 

.61 

.63 

.65 

.67 

4.6 

.46 

.48 

.51 

.53 

.55 

.57 

.60 

.62 

.64 

.67 

.6f 

4.7 

.47 

.49 

.52 

.54 

.56 

.59 

.61 

.63 

.66 

.68 

.7C 

4.8 

.48 

.50 

.53 

.55 

58 

.60 

.62 

.65 

.67 

.70 

.72 

4.9 

.49 

.51 

.54 

.66 

.59 

.61 

.64 

.66 

.69 

.71 

.73 

5.0 

.50 

.52 

.55 

.57 

.60 

.62 

.65 

.67 

.70 

.72 

.76 

5.1 

.51 

.54 

.56 

.59 

.61 

.64 

.66 

.69 

.71 

.74 

.76 

5.2 

.52 

.55 

.57 

.60 

.62 

.65 

.68 

.70 

.73 

.75 

.78 

5.3 

.53 

.56 

.58 

.61 

.64 

.66 

.69 

.72 

.74 

.77 

.79 

5.4 

.54 

.57 

.59 

.62 

.65 

.67 

.70 

.73 

.76 

.78 

.81 

5.5 

.55 

.58 

.60 

.63 

.66 

.69 

.71 

.74 

.77 

.80 

.82 

5.6 

.56 

.59 

.62 

.64 

.67 

.70 

.73 

.76 

.78 

.81 

.84 

5.7 

.57 

.60 

.63 

.66 

.68 

.71 

.74 

.77 

.80 

.83 

.85 

5.8 

.58 

.61 

.64 

.67 

.70 

.72 

.75 

-.78 

.81 

.84 

.87 

5.9 

.59 

.62 

.65 

.68 

.71 

.74 

.77 

.80 

.83 

.86 

.88 

6.0 

.60 

.63 

.66 

.60 

.72 

.75      .78 

.81 

.84 

.87 

.90 

272 


Testing  Milk  and  Its  Products. 


Table   X.    Relative-value  tables  ( Continued). 


J 

fl 

S"Je 

Price  of  milk  per  100  pounds,  in  dollars  and  cents. 

r 

3.0 

.46 

.48 

.49 

.51 

.52 

.54 

.55 

.57 

.58 

.60 

3.1 

.48 

.50 

.51 

.53 

.54 

.56 

.57 

.69 

.60 

.62 

3.2 

.50 

.51 

.53 

.54 

.56 

.58 

.59 

.61 

.62 

.64 

3.3 

.51 

.53 

.54 

.56 

.58 

.59 

.61 

.63 

.64 

.66 

3  4 

.53 

.54 

.56 

58 

.59 

61 

.63 

65 

.66 

68 

3.5 

.54 

.56 

.58 

.59 

.61 

.63 

.65 

.66 

.68 

.70 

3.6 

.56 

.58 

.59 

61 

.63 

.65 

.67 

.68 

.70 

.72 

8.7 

.57 

.69 

.61 

.63 

.65 

.67 

.68 

.70 

.72 

.74 

8  8 

.59 

.61 

.63 

65 

.66 

68 

.70 

7? 

.74 

76 

3.9 

.60 

.62 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

4  0 

.62 

.64 

.66 

68 

.70 

7?, 

.74 

76 

.78 

80 

4.1 

.64 

.66 

.68 

.70 

.72 

.74 

.76 

.78 

.80 

.82 

4.2 

.65 

.67 

.69 

.71 

.73 

.76 

.78 

.80 

.82 

.84 

4.3 

.67 

.69 

.71 

.73 

.75 

.77 

.80 

.82 

.84 

.86 

4.4 

.68 

.70 

.73 

.75 

.77 

.79 

.81 

.84 

.86 

.88 

4.5 

.70 

.72 

.74 

.76 

.79 

.81 

.83 

.85 

.88 

.90 

4  6 

.71 

.74 

.76 

78 

.80 

83 

.85 

87 

.90 

92 

4.7 

.73 

.75 

.78 

.80 

.82 

.85 

.87 

.89 

.92 

.94 

4.8 

.74 

.77 

.79 

.82 

.84 

.86 

.89 

.91 

.94 

.96 

4.9 

.76 

.78 

.81 

.83 

.86 

.88 

.91 

.93 

.96 

.98 

5.0 

.77 

.80 

.82 

.85 

.87 

.90 

.92 

.95 

.97 

1.00 

5.1 

.79 

.82 

.84 

.87 

.89 

.92 

.94 

.97 

.99 

1.02 

5.2 

.81 

.83 

.86 

.88 

.91 

.94 

.96 

.99 

1.01 

1.04 

5.3 

.83 

.85 

.87 

.90 

.93 

.95 

.98 

1.01 

1.03 

1.06 

5.4 

.84 

.86 

.89 

.92 

.94 

.97 

1.00 

1.03 

1.05 

1.08 

5.5 

.85 

.88 

.91 

.93 

.96 

.99 

1.02 

1.04 

1.07 

1.10 

5.6 

.87 

.90 

.92 

.95 

.98 

1.01 

1.04 

1.06 

1.09 

1.12 

5.7 

.88 

.91 

.94 

.97 

1.00 

1.03 

1.05 

1.08 

1.11 

1.14 

5.8 

.90 

.93 

.96 

.99 

1.01 

1.04 

1.07 

1.10 

1.13 

1.16 

5.9 

.91 

.94 

.97 

1.00 

1.03 

1.06 

1.09 

1.12 

1.15 

1.18 

6.0 

.93 

.96 

.99 

1.02 

1.05 

1.08 

1.11 

1.14 

1.17 

1.20 

Appendix. 


273 


Table   X.    Relative-value  tables  (Continued). 


Per  cent.  II 
fat. 

Price  of  milk  per  100  pounds,  in  dollars  and  cents. 

3.0 

.61 

.63 

.64 

.66 

.67 

.69 

.70 

.72 

.73 

.75 

3.1 

.64 

.65 

.67 

.68 

.70 

.71 

.73 

.74 

.76 

.78 

3.2 

.66 

.67 

.69 

.70 

.72 

.74 

.75 

.77 

.78 

.80 

3.3 

.68 

.69 

.71 

.73 

.74 

.76 

.78 

.79 

.81 

.83 

3.4 

.70 

.71 

.73 

.75 

.76 

.78 

.80 

.82 

.83 

.85 

3.5 

.72 

.73 

.75 

.77 

.79 

.80 

.82 

.84 

.86 

.88 

3.6 

.74 

.76 

.77 

.79 

.81 

.83 

.85 

.86 

.88 

.90 

3.7 

.76 

.78 

.80 

.81 

.83 

.85 

.87 

.89 

.91 

.93 

3.8 

.78 

.80 

.82 

.84 

.85 

.87 

.89 

.91 

.93 

.95 

3.9 

.80 

.82 

.84 

.86 

.88 

.90 

.92 

.94 

.96 

.98 

4.0 

.82 

.84 

.86 

.88 

.90 

,92 

.94 

.96 

.98 

1.00 

4.1 

.84 

.86 

.88 

.90 

.92 

,94 

.96 

.98 

1.00 

1.03 

4.2 

.86 

.88 

.90 

.92 

.94 

.97 

.99 

1.01 

1.03 

1.05 

4.3 

.88 

.90 

.92 

.95 

.97 

.99 

1.01 

1.03 

1.05 

1.08 

4.4 

.90 

.92 

.95 

.97 

.99 

1.01 

1.03 

1.06 

1.08 

1.10 

4.5 

.92 

.94 

.97 

.99 

1.01 

1.03 

1.06 

1.08 

1.10 

1.13 

4.6 

.94 

.97 

.99 

1.01 

1.03 

1.06 

1.08 

1.10 

1.13 

1.15 

4.7 

.96 

.99 

1.01 

1.03 

1.06 

1.08 

1.10 

1.13 

1.15 

1.18 

4.8 

.98 

1.01 

1.03 

1.06 

1.08 

1.10 

1.13 

1.15 

1.18 

1.20 

4.9 

1.00 

1.03 

1.05 

1.08 

1.10 

1.13 

1.15 

1.18 

1.20 

1.23 

5.0 

1.02 

1.05 

1.07 

1.10 

1.12 

1.15 

1.18 

1.20 

1.23 

1.25 

5.1 

1.05 

1.07 

1.10 

1.12 

1.15 

1.17 

1.20 

1.22 

1.25 

1.27 

5.2 

1.07 

1.09 

1.12 

1.14 

1.17 

1.20 

1.22 

1.25 

1.27 

1.30 

5.3 

1.09 

1.11 

1.14 

1.17 

1.19 

1.22 

1.25 

1.27 

1.30 

1.32 

5.4 

1.11 

1.13 

1.16 

1.19 

1.21 

1.24 

1.27 

1.30 

1.32 

1.35 

5.5 

1.13 

1.15 

1.18 

1.21 

1.24 

1.26 

1.29 

1.32 

1.35 

1.38 

5.G 

1.15 

1.18 

1.20 

1.23 

1.26 

1.29 

1.32 

1.34 

1.37 

1.40 

5.7 

1.17 

1.20 

1.23 

1.25 

1.28 

1.31 

1.34 

1.37 

1.39 

1.43 

5.8 

1.19 

1.22 

1.25 

1.28 

1.30 

1.33 

1.36 

1.39 

1.42 

1.45 

5.9 

1.21 

1.24 

1.27 

1.30 

1.33 

1.36 

1.39 

1.42 

1.45 

1.48 

6.0 

1.23 

1.26 

1.29 

1.32 

1.35 

1.38 

1.41 

1.44 

1.47 

1.50 

18 


274 


Testing  Milk  and  Its  Products. 


Table   X.    Relative-value  tables  (Continued). 


Percent.  1 
fat. 

1 
Price  of  milk  jwr  100  pounds,  in  dollars  and  cents. 

3.0 

.76 

.78 

.79 

.81 

.82 

.84 

.85 

.87 

\ 

.88 

.90 

3.1 

.79 

.81 

.82 

.84 

.85 

.87 

.88 

.90        .91 

.93 

3.2 

.82 

.83 

.85 

.86 

.88 

.90 

.91 

.93        .94 

.96 

3.3 

.84 

.86 

.87 

.89 

.91 

.92 

.94 

.96 

.97 

.99 

3.4 

.87 

.88 

.90 

.92 

.93 

.95 

.97 

.99 

1.00 

1.02 

3.5 

.89 

.91 

.93 

.94 

.96 

.98 

1.00 

1.01 

1.03 

1.05 

3.6 

.92 

.94 

.95 

.97 

.99 

1.00 

1.03 

1.04 

1.06 

1.08 

3.7 

.94 

.96 

.98 

1.00 

1.02 

1.03 

1.05 

1.07 

1.09 

1.11 

3.8 

.07 

.99 

1.01 

1.03 

1.04 

1.06 

1.08 

1.10 

1.12 

1.14 

3.9 

.99 

1.01 

1.03 

1.05 

1.07 

1.09 

1.11 

1.13 

1.15 

1.17 

4.0 

1.02 

1.01 

1.06 

1.08 

1.10 

1.12 

1.14 

1.16 

1.18 

1.20 

4.1 

1.05 

1.07 

1.09 

1.11 

1.13 

1.15 

1.17 

1.19 

1.21 

1.23 

4.2 

1.07 

1.09 

1.11 

1.13 

1.15 

1.18 

1.20 

1.22 

1.24 

1.26 

4.3 

1.10 

1.12 

1.14 

1.16 

1.18 

1.20 

1.23 

1.25 

1.27 

1.29 

4.4 

1.12 

1.14 

1.17 

1.19 

1.21 

•1.23 

1.25 

1.28 

1.30 

1.32 

4.5 

1.15 

1.17 

1.19 

1.21 

1.24 

1.26 

1.28 

1.30 

1.33 

1.35 

4.6 

1.17 

1.20 

1.22 

1.24 

1.26 

1.29 

1.31 

1.33 

1.36 

1.38 

4.7 

1.20 

1.22 

1.25 

1.27 

1.29 

1.32 

1.34 

1.36 

1.39 

1.41 

4.8 

1.22 

1.25 

1.27 

1.30 

1.32 

1.34 

1.37 

1.39 

1.42 

1.44 

4.9 

1.25 

1.27 

1.30 

1.32 

1.35 

1.37 

1.40 

1.42 

1.45 

1.47 

5.0 

1.27 

1.30 

1.32 

1.35 

1.37 

1.40 

1.42 

1.45 

1.47 

1.50 

5.1 

1.30 

1.33 

1.35 

1.38 

1.40 

1.43 

1.45 

1.48 

1.50 

1.53 

5.2 

1.33 

1.35 

1.37 

1.40 

1.43 

1.46 

1.48 

1.51 

1.53 

1.56 

5.3 

1.35 

1.38 

1.40 

1.43 

1.46 

1.48 

1.51 

1.54 

1.56 

1.59 

5.4 

1.38 

1.40 

1.43 

1.46 

1.48 

1.51 

1.54 

1.57 

1.59 

1.62 

5.5 

1.40 

1.43 

1.46 

1.48 

1.51 

.54 

1.57 

1.60 

1.62 

1.65 

5.6 

1.43 

1.46 

1.48 

1.51 

1.54 

.57 

1.60 

1.62 

1.65 

1.68 

5.7 

1.45 

1.48 

1.51 

1.54 

1.57 

.60 

,.<J2 

1.65 

1.68 

1.71 

5.8 

1.48 

1.51 

1.54 

1.57 

1.59 

.62 

1.65 

1.68 

1.71 

1.74 

5.9 

•1.50 

1.53 

1.56 

1.59 

1.62 

.65 

1.68 

1.71 

1.74 

1.77 

6.0 

1.53 

1.56 

1.59 

1.62 

1.65 

.68 

1.71 

1.74 

1.77 

1.80 

Appendix.  275 

Table  XI.  Butter  chart,  showing  calculated  yield  of  butter  (in 
Ibs.)  from  I  to  10,000  Ibs.  of  milk,  testing  3.0  to  5.3  per 
cent.  (See  directions  for  use,  p.  262. ) 


i 

3.00 

3.10 

3.20 

3.30 

3.40 

3.50 

3.60 

3.70 

3.80 

3.90 

4.00 

4.10 

% 

H 

**• 

Milk, 

Milk, 

Ibs. 

Ibs.' 

10,000 

325 

336 

348 

360 

371 

383 

394 

406 

418 

429 

441 

452 

10,000 

9,000 

293 

302 

313 

324 

334 

345 

355 

365 

376 

386 

397 

407 

9,000 

8,000 

260 

269 

278 

288 

297 

306 

315 

325 

334 

343 

353 

362 

8,000 

7,000 

228 

235 

244 

252 

260 

268 

276 

284 

293 

300 

309 

316 

7,000 

6,000 

195 

202 

209 

216 

223 

230 

236 

244 

251 

257 

265 

271 

6,000 

5,000 

163 

168 

174 

180 

186 

192 

197 

203 

209 

215 

221 

226 

5,000 

4,000 

130 

134 

139 

144 

148 

153 

158 

162 

167 

172 

176 

181 

4,000 

3,000 

97.5 

101 

104 

108 

111 

115 

118 

122 

125 

129 

132 

136 

3,000 

2,000 

65.0 

67.2 

69.6 

72.0 

74.2 

76.6 

78.8 

81.2 

83.6 

85.8 

88.2 

90.4 

2,000 

1,000 

32.5 

33.6 

34.8 

36.0 

37.1 

38.3 

39.4 

40.6 

41.8 

43.9 

44.1 

45.2 

1,000 

900 

29.3 

30.2 

31.3 

32.4 

33.4 

34.5 

35.5 

36.5 

37.6 

38.6 

39.7 

40.7 

900 

800 

26  0 

ft6  9 

ft7  8 

98  8 

ft9  7 

30  6 

31  5 

8ft  5 

88  4 

84  3 

85  3 

86  2 

800 

700 

22.8 

23.5 

24.4 

25.2 

26.0 

26.8 

27.6 

28.4 

29.3 

30.0 

30.9 

31.6 

700 

600 

19  5 

ftO  ft 

ftO  9 

21  6 

ftft  3 

ft3  0 

ft3  6 

ft4  4 

ft5  1 

ft5  7 

•?f>  5 

ft7  1 

600 

500 

16.3 

16.8 

17.4 

18.0 

18.6 

19.2 

19.7 

20.3 

20.9 

21.5 

22.1 

22.6 

500 

400 

13.0 

13.4 

13.9 

14.4 

14.8 

15.3 

15.8 

16.2 

16.7 

17.2 

17.6 

18.1 

400 

300 

9  7 

10  1 

10  4 

10  8 

11  1 

11  5 

11  8 

1ft  ft 

1ft  5 

1ft  9 

13  ft 

13  6 

300 

200 

6.5 

6.7 

6.9 

7.2 

7.4 

7.6 

7.9 

8.1 

8.3 

8.6 

8.8 

9.0 

200 

100 

3.2 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

4.1 

4.2 

4.3 

4.4 

4.5 

100 

90 

2.9 

3.0 

3.1 

3.2 

3.3 

3.4 

3.5 

8.6 

3.7 

3.8 

3.9 

4.1 

90 

80 

2.6 

2.7 

2.8 

2.9 

3.0 

3.1 

3.2 

3.3 

3.4 

3.4 

3.5 

3.6 

80 

70 

2.3 

2.3 

2.4 

2.5 

2.6 

2.7 

2.8 

2.8 

2.9 

3.0 

3.1 

3.2 

70 

60 

1.9 

2.0 

2.1 

2.2 

2.2 

2.3 

2.4 

2.4 

2.5 

2.6 

2.7 

2.7 

60 

50 

1  6 

1  7 

1  7 

1  8 

1  9 

1  9 

ft  0 

ft  0 

ft  1 

ft  ft 

ft  ft 

ft  3 

50 

40 

1.3 

1.3 

1.4 

1.4 

1.5 

1.5 

1.6 

1.6 

1.7 

1.7 

1.8 

1.8 

40 

30 

1.0 

1.0 

1.0 

1.1 

1.1 

1.2 

1.2 

1.2 

1.3 

1.3 

1.3 

1.4 

30 

20 

.6 

.7 

.7 

.7 

.7 

.8 

.8 

.8 

.8 

.9 

.9 

.9 

20 

10 

8 

3 

4 

4 

4 

4 

4 

4 

4 

4 

4 

5 

10 

9 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

.4 

.4 

.4 

.4 

9 

8 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

8 

7 

.2 

.2 

.2 

.8 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

7 

6 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

6 

5 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

o 
,4 

5 

4 

.1 

.1 

.1 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

8 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

3 

2 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

1 

1 

T 

3.00 

3.10 

3.20 

3.30 

3.40 

3.50 

3.60 

3.70 

3.80 

3.90 

4.00 

4.10 

\ 

276 


Testing  Milk  and  Its  Products. 


Table  XI.    Butter  chart  ( Continued). 


-M 

1 

4.20 

4.30 

4.40 

4.50 

4.60 

4.70 

4.80 

4.90 

5.00 

5.10 

5.20 

:>.30 

S 

O3 

Milk 

Milk 

Ibs. 

Ibs, 

10,000 

464 

476 

487 

499 

510 

522 

534 

545 

557 

568 

580 

592 

10,000 

9,000 

418 

428 

438 

449 

459 

470 

481 

491 

501 

511 

522 

533 

9,000 

8,000 

371 

381 

390 

399 

408 

418 

427 

436 

446 

454 

464 

474 

8,000 

7,000 

325 

333 

341 

349 

357 

365 

374 

382 

390 

398 

406 

414 

7,000 

6,000 

278 

286 

292 

299 

306 

313 

320 

327 

334 

341 

348 

355 

6,000 

5,000 

232 

238 

244 

250 

255 

261 

267 

273 

279 

284 

290 

296 

5,000 

4,000 

186 

190 

195 

200 

204 

209 

214 

218 

223 

227 

232 

.237 

4,000 

3,000 

139 

143 

146 

150 

153 

157 

160 

164 

167 

170 

174 

17b 

3,000 

2,000 

92.8 

95.2 

97.4 

99.8 

102 

104 

107 

109 

111 

114 

116 

118 

2,000 

1,000 

46.4 

47.6 

48.7 

49.9 

51.0 

52.2 

53.4 

54.5 

55.7 

56.8 

58.0 

59.2 

1,000 

900 

41.8 

42.8 

43.8 

44.9 

45.9 

47.0 

48.1 

49.1 

50.1 

51.1 

52.2 

>3.3 

900 

800 

37.1 

38.1 

39.0 

39.9 

40.8 

41.8 

42.7 

43.6 

44.6 

45.4 

46.4 

47.4 

800 

700 

32  5 

33  3 

84  1 

34  9 

35  7 

36  5 

37  4 

38  ?, 

39  0 

39  8 

40  6 

41  4 

700 

600 

27.8 

28.6 

29.2 

29.9 

30.6 

31.3 

32.0 

32.7 

33.4 

34.1 

34.8 

35.5 

600 

500 

23.2 

23.8 

24.4 

25.0 

25.5 

26  .-1 

26.7 

27.3 

27.9 

28.4 

21).  0 

29.6 

500 

400 

18  6 

19  0 

19  5 

?0  0 

?0  4 

?0  9 

91  4 

*>1  8 

99  3 

99  7 

93  2 

23  7 

400 

300 

13.9 

14.3 

14.6 

15.0 

15.3 

15.7 

16.0 

16.4 

16.7 

17.0 

17.4 

17.8 

300 

200 

9.3 

9.5 

9.7 

10.0 

10.2 

10.4 

10.7 

10.9 

11.1 

11.4 

11.6 

11.8 

200 

100 

4.6 

4.8 

4.9 

5.0 

5.1 

5.2 

5.3 

5.5 

5.6 

5.7 

5.8 

5.9 

100 

90 

4.2 

4.3 

4.4 

4.5 

4.6 

4.7 

4.8 

4.9 

5.0 

5.1 

5.2 

5.3 

90 

80 

3.7 

3.8 

3.9 

4.0 

4.1 

4.2 

4.3 

4.4 

4.5 

4.5 

4.6 

4.7 

80 

70 

3.3 

3.3 

3.4 

3.5 

3.6 

3.7 

3.7 

3.8 

3.9 

4.0 

4.1 

4.1 

70 

60 

2.* 

2.9 

2.9 

3.0 

3.1 

3.1 

3.2 

3.3 

3.3 

3.4 

3.5 

3.0 

60 

50 

2.3 

2.4 

2.4 

2.5 

2.6 

2.6 

2.7 

2.7 

2.8 

2.8 

2.9 

3.0 

50 

40 

1.9 

1.9 

2.0 

2.0 

2.0 

2.1 

2.1 

2.2 

2.2 

2.3 

2.3 

2.4 

40 

30 
9fi 

1.4 

1.4 
i  n 

1.5 
1(\ 

1.5 
i  n 

1.5 
i  n 

1.6 
i  A 

1.6 

1.6 

1.7 

1.7 

1.7 

1.8 

19 

30 

9ft 

zo 
10 

.5 

j.  .  \j 
.5 

.u 
.5 

JL  .U 

.5 

JL.U 

.5 

-L  .  U 

.5 

.5 

.6 

.6 

.6 

.6 

.  L 

.6 

fni 

10 

9 

.4 

.4 

.4 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

9 

8 

4 

4 

4 

4 

4 

4 

4 

4 

5 

.5 

5 

5 

8 

7 

3 

3 

3 

4 

4 

4 

/| 

4 

4 

4 

4 

4 

7 

»6 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.4 

.4 

6 

5 

.2 

.2 

.2 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

.3 

5 

4 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

4 

« 

.1 

.1 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

.2 

3 

r 

A 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

2 

l 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

.1 

1 

4 

P 

4.20 

4.30 

4.40 

4.50 

4.60 

4.70 

4.80 

4.90 

5.  CO 

5.10 

5.20 

5.30 

2 

P 

F+ 

Appendix. 


277 


Table  XII.  Overrun  table,  showing  pounds  of  butter  from 
one  hundred  Ibs.  of  milk.  (See  directions  for  use, 
p.  198.) 


Per 

cent, 
fat. 

1.10 

1.11 

1.12 

1.13 

1.14 

1.15 

1.16 

1.17 

1.18 

1.19 

1.20 

Per 

cent, 
fat. 

3.0 
3.1 

3.2 
3.3 
3.4 

3.5 
3.6 
3.7 

3  8 

3.30 
3.41 
3.52 
8  63 

3.33 
3.44 
3.55 
3  66 

3.36 
3.47 
3.58 
8  70 

3.39 
3.50 
3.62 
3  73 

3.42 

8.53 
8.65 
8  76 

3.45 
3.57 

3.68 
-">»  80 

3.48 
3.60 
3.71 

8  83 

3.51 
3.63 
3.74 
3  86 

3.54 

3.66 

3.78 
3  89 

3.57 

3.68 
3.81 
3  98 

3.60 
3.72 

3.84 
8  96 

3.0 
3.1 
3.2 
3.3 
3.4 

3.5 
3.6 
3.7 

1  3.8 
3.9 

4.0 
4.1 
4.2 
4.3 
4.4 

4.5 
4.6 
4.7 
4.8 
4.9 

5.0 
5.1 
5.2 
5.3 
5.4 

5.5 
5.6 
5.7 

5.8 
5.9 
6.0 

3.74 

3.85' 
3.96 
4.07 
4  18 

3.77 

3.89 
4.00 
4.11 

4  99 

3.81 

8.92 
4.03 
4.14 
4  9fl 

3.84 

3.96 
4.07 
4.18 
4  99 

3.88 

3.99 
4.10 
4.22 
4  33 

3.91 

4.03 
4.14 
4.26 
-1  87 

3.94 

4.06 
4.18 

4.29 
4  41 

3.98 

4.10 
4.21 
4.33 
4  45 

4.01 

4.13 
4.25 
4.37 
4  48 

4.05 

4.17 

4.28 
4.40 
1  5k> 

4.08 

4.20 
4.32 
4.44 
4.56 

3.9 

4  99 

4  88 

4  37 

4  41 

4  45 

4  49 

4  59 

4  56 

4  60 

4  64 

4  68 

4.0 
4.1 
4.2 

4.40 
4.51 
4  6? 

4.44 
4.55 
4  66 

4.48 
4.59 
4  70 

4.5!> 
4.03 
4  7r> 

4.56 
4.67 
4  79 

1.60 
4.72 
4  83 

4.64 
4.76 
4  87 

4.68 
4.80 
4  91 

4.72 
4.84 
4  96 

4.76 

4.88 
"i  00 

4.80 
4.92 
5  04 

4.3 
4.4 

4.73 
4  84 

4.77 

4  88 

4.82 
4  98 

4.86 
4  97 

4.90 
5  09 

4.95 
i  06 

4.99 
=>  10 

5.03 
5  15 

5.07 
5  19 

5.12 
5  94 

5.16 
5  98 

4.5 
4.6 
4.7 
4.8 
4.9 

4.95 
5.0G 
5.17 

5.28 
5  39 

5.00 
5.11 
5.22 
5.33 
5  44 

5.04 
5.15 
5.26 

5.38 
5  49 

5.09 
5.20 
5.31 
5.42 
5  54 

5.13 
5.24 
5.36 
5.47 
5  59 

5.18 
5.29 
5.41 
5.5'-> 

5  64 

5.22 
5.34 
5.45 
5.57 
5  68 

5.27 

5.38 
5.49 
5.62 
5  73 

5.31 
5.43 
5.55 
5.66 
5  78 

5.36 
5.47 
5.59 
5.71 

5  83 

5.40 
5.52 
5.64 
5.7« 
5  88 

5.0 
5.1 
5.2 
5.3 

5.50 
5.61 
5.72 
5  83 

5.55 
5.66 
5.77 
5  88 

5.60 
5.71 
5.82 
5  94 

5.65 
5.76 

5.88 
5  99 

5.70 
5.81 
5.93 
6  04 

5.75 

5.87 
5.98 
6  10 

5.80 
5.92 
6.03 
6  15 

5.85 
5.97 
6.08 
6  90 

5.90 
6.02 
6.14 
6  95 

5.95 
6.07 
6,19 
6  31 

6.00 
6.12 
6.24 
6  36 

5.4 
5.5 

5.94 
6  05 

5.99 
6  11 

8.05 
6  16 

6.10 

6  99 

6.16 

6  97 

6.21 
6  33 

6.26 
6  38 

6.32 
6  44 

6.37 
6  49 

6.43 
6  55 

6.48 
6  60 

5.6 

6  16 

6  9?l 

6  97 

6  33 

6  38 

6  44 

6  50 

6  55 

6  61 

6  66 

6  79 

5.7 
5.8 

6.27 
6  38 

6.33 
6  44 

6.38 
6  50 

6.44 

6  55 

6.50 
6  61 

6.56 
6  67 

6.61 
6  73 

6.67 
6  79 

6.73 

6  84 

6.78 
6  90 

6,84 
6  96 

5.9 
6.0 

6.49 
6  60 

6.55 
6  66 

6.61 
6,7?, 

6.67 
6  78 

6.73 

fi  84 

6.79 
6  90 

6.84 
6  96 

6.90 
7  09, 

6.96 

7  08 

7.02 
7  14 

7.08 
7  90 

278 


Testing  Milk  and  Its  Products. 


Table  XIII.  Yield  of  Cheese  from  100  Ibs.  milkwith2  5  to  6'per  cent 
of  fat,  and  lactometer  readings  from  26  to  30.  (See  p.  200) 


«J 

LACTOM  KTKK  UKUUKKS. 

C-M 

r  ••-» 

f° 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

5  o 

2  ft 

7.28 

7.41 

7.54 

7  67 

7.81 

7.94 

8.07 

8.20 

8.33 

8.47 

8  6'  ' 

2.5 

2.6 

7.44 

7.57 

7.70 

7.83 

7.96 

8.09 

8.22 

8.35 

8.49 

8.62 

8.76 

2.7 

7.59 

7.72 

7.85 

7.99 

8.1* 

8.25 

8.38 

8.51 

8.64 

8.77 

8.91 

L.I 

2  8 

7.74 

7.87 

8.00 

8  14 

8.27 

8.40 

8.53 

8.67 

8.80 

8.94 

9.07 

?  ft 

O      Q 

7.90 

8.03 

8.16 

8  30 

8.44 

8.56 

8.69 

8.82 

8.95 

9.i'9 

9.22 

2.9 

3.0 

8.05 

8.18 

8.31 

8.4ft 

8.58 

8.71 

8.84 

8.97 

9.11 

9.24 

vi.  37 

3.0 

3.1 

8.21 

8.34 

8.47 

8.60 

8/74 

8.87 

9.00 

9.13 

9.26 

9.39 

9.53 

3.1 

3.2 

8.36 

8.4u 

8.62 

8.75 

8.89 

9.02 

9.15 

9.28 

9.42 

9.55 

9.68 

3.2 

3.3 

8.52 

8i65 

8.78 

8.91 

9.05 

9.18 

9.31 

9.44 

9.57 

9.70 

9.84 

3.3 

3  4 

8.67 

8.80 

8.93 

9  OH 

9.20 

9.33 

9.46 

9.59 

9.73 

9.86 

9.9U 

3  4 

3.  ft 

8.82 

8.96 

9.09 

9.22 

9.35 

9.  '8 

9.62 

9.75 

9.88 

10.01 

10.  1- 

3.5 

3.6 

8.98 

9.11 

9.24 

9.37 

9.50 

9.63 

9.7: 

9.90 

10.03 

10.17 

10.30 

3.6 

3  7 

9.13 

9.26 

9.39 

9  ft? 

9.65 

9.7s 

9.92 

10.05 

10.19 

10.32 

10.46 

3  7 

9.29 

0.42 

9.55 

9.68 

9.81 

9.94 

1«  .21 

10.34 

10.48 

10.61 

3.8 

3*.9 

9.44 

9.57 

9.70 

9.84 

9.97 

10.10 

10/23 

10.36 

10.50 

10.04 

10.77 

3.9 

4.0 

9.60 

9.73 

9.86 

10.00 

10.13 

10.26 

10.39 

10.53 

10.66 

10.79 

10.93 

4.0 

4.1 

9.75 

9.88 

10.02 

,0.15 

10.28 

10.39 

10.54 

10.68 

10.81 

10.94 

11.08 

4.1 

4  *> 

9  90 

10.03 

10.17 

10.30 

10.43 

10.57 

10.70 

10.84 

10.97 

11.10 

11.24 

4  2 

4.3 

10.06 

10.19 

10.32 

10.45 

10.58 

10.72 

10.85 

10.99 

11.12 

11.25 

11.39 

4.3 

4.4 

10.21 

10.34 

10.48 

10.61 

10.74 

10.87 

11.00 

11.14 

11.27 

11.41 

11.55 

4.4 

4.5 

10.36 

10.49 

10.63 

10.76 

10.89 

11.03 

11.16 

11.29 

11.42 

11.56 

11.70 

4.5 

4.6 

10.52 

10.65 

10.78 

10.92 

11.05 

11.18 

11.31 

11.45 

11.58 

H.71 

11.85 

4.6 

4.7 

10.67 

10.81 

10.94 

11.  Of 

11.20 

11.34 

11.47 

11.60 

11.73 

11.87 

12.0 

1.7 

4.8 

10.KS 

10.96 

11.09 

11.22 

11.36 

11.49 

11.62 

11.76 

11.89 

i2.02 

12.16 

4.8 

4.9 

10.98 

11.11 

11.25 

11.38 

11.51 

11.65 

11.78 

11.91 

12.04 

12.18 

12.32 

4.9 

5.0 

11.14 

11.27 

11.40 

11.54 

11.67 

11.80 

11.93 

12.07 

12.20 

12.34 

12.48 

0.0 

5.1 

11.29 

11.42 

11.55 

11.69 

11.82 

11.96 

12.09 

12.23 

12.36 

12.49 

12.63 

o.l 

5.2 

11.45 

11.58 

11.71 

11.85 

11.98 

12.11 

12.24 

12.38 

12.52 

12.66 

12.80 

o.2 

5.3 

11.60 

11.73 

11.86 

11.99 

12.13 

12.27 

12.40 

12.53 

12.67 

12.71 

12.8 

5.3 

5.4 

11.76 

11.89 

12.02 

12.16 

12.29 

12.42 

12.55 

12.69 

12.83 

12.97 

3.01 

o.4 

5.5 

11.91 

12.04 

12.17 

12.31 

12.44 

12.58 

12.71 

12.85 

12.99 

13.12 

13.25 

5.5 

•5.  (3 

12.07 

12.20 

12.33 

12.47 

12.60 

12.73 

12.87 

13.00 

13.14 

13.  28 

13.41 

0.6 

5.7 

12.22 

12.35 

12.48 

12.62 

12.75 

12.89 

13.02 

13.16 

I3.3i 

13.44 

13.  .-7 

.7 

5.8 

12.38 

12.51 

12.64 

12.77 

12.91 

13.05 

13.18 

13.31 

13.45 

13.  M) 

13.72 

>.8 

5.9 

12.53 

12.66 

12.79 

12.93 

13.06 

13.19 

13.33 

13.47 

13.6i 

13.74 

13.87 

o.9 

6.0 

12.  6y 

12.82 

12.95 

13.09 

13.22 

13.35 

13.49 

13.6. 

13.7;") 

13.8U 

14.02 

(5.0 

Appendix. 


279 


fable  XIV.    Comparisons  of  Fahrenheit  and  Centigrade 
(Celsius)  thermometer  scales. 


Fahren- 
heit. 

Centi- 
grade. 

Fahren- 
heit. 

Centi- 
grade. 

Fahren- 
heit. 

Centi- 
grade. 

+212 

+100 

+176 

+80 

+140 

+60 

211 

99.44 

175 

79.44 

139 

59.44 

210 

98.89 

174 

78.89 

138 

58.89 

209 

98.33 

173 

78.33 

137 

58.33 

208 

97.78 

172 

77.78 

136 

57.78 

207 

97.22 

171 

77.22 

135 

57.22 

206 

96.67 

170 

76.67 

134 

56.67 

205 

96.11 

169 

76.11 

133 

56.11 

204 

95.55 

168 

75.55 

132 

55.55 

203 

95 

167 

75 

131 

55 

202 

94.44 

166 

74.44 

130 

54.44 

201 

93.89 

165 

73.89 

129 

53.89 

200 

93.33 

164 

72.33 

128 

53.33 

199 

92.78 

163 

72.78 

127 

52.78 

198 

92.22 

162 

71.22 

126 

52.22 

197 

91.67 

161 

71.67 

125 

51.67 

196 

91.11 

160 

71.11 

124 

51.11 

195 

90.55 

159 

70.55 

123 

50.55 

194 

90 

158 

70 

122 

50 

193 

89.44 

157 

69.44 

121 

49.44 

192 

88.89 

156 

68.89 

120 

48.89 

191 

88.33 

155 

68.33 

119 

48.33 

190 

87.78 

154 

67.78 

118 

47.78 

189 

87.22 

153 

67.22 

117 

47.22 

188 

86.67 

152 

66.67 

116 

46.67 

187 

86.11 

151 

66.11 

115 

46.11 

186 

85.55 

150 

65.55 

114 

45.55 

185 

85 

149 

65 

113 

45 

184 

84.44 

148 

64.44 

112 

44.44 

183 

83.89 

147 

63.89 

111 

43.89 

182 

83.33 

146 

63.33 

110 

43.33 

181 

82.78 

145 

62.78 

109 

42.78 

180 

82.22 

144 

62.22 

108 

42.22 

179 

81.67 

143 

61.67 

107 

41.67 

178 

81.11 

142 

61.11 

106 

41.11 

177 

80.55 

141 

60.55 

105 

40.55 

280 


Testing  Milk  and  Its  Products. 


Table  XIV.    Comparisons  of  thermometer  scales  ( Continued. ) 


Fahren- 
heit. 

Centi- 
grade. 

Fahren- 
heit. 

Centi- 
grade. 

Fahren- 
heit. 

Centi- 
grade. 

+104 

+40 

+68 

+20 

+32 

+o 

103 

39.44 

67 

19.44 

31 

—0.55 

102 

38.89 

66 

'  18.89 

30 

1.11 

101 

38.33 

65 

18.33 

29 

1.67 

100 

37.78 

64 

17.78 

28 

2.22 

99 

37.22 

63 

17.22 

27 

2.78 

98 

36.67 

62 

16.67 

26 

3.33 

97 

36.11 

61 

16.11 

25 

3.89 

96 

35.55 

60 

15.55 

24 

4.44 

95 

35 

59 

15 

23 

5 

94 

34.44 

58 

14.44 

22 

5.55 

93 

33.89 

57 

13.89 

21 

6.11 

92 

33.33 

56 

13.33 

20 

6.67 

91 

32.78 

55 

12.78 

19 

7.22 

90 

32  22 

54 

12.22 

18 

7.78 

89 

31.67 

53 

11.67 

17 

8.33 

88 

31.  11 

52 

11.11 

16 

8.89 

87 

30.55 

51 

10.55 

15 

9.44 

86 

30 

50 

10 

14 

10 

85 

29.44 

49 

9.44 

13 

10.55 

84 

28.89 

48 

8.89- 

12 

11.11 

83 

28.33 

47 

8.33 

11 

11.67 

82 

27.78 

46 

7.78 

10 

12.22 

81 

27.22 

45 

7.22 

9 

12.78 

80 

26.67 

44 

6.67 

8 

13.33 

79 

26.11 

43 

6.11 

7 

13.89 

78 

25.55 

42 

5.55 

6 

14.44 

77 

25 

41 

5 

5 

15.00 

76 

24.44 

40 

4.44 

4 

15.55 

75 

23.89 

39 

3.89 

3 

16.11 

74 

23.33 

38 

3.33 

2 

16.67 

73 

22.78 

37 

2.78 

1 

17.22 

72 

22.22 

36 

2.22 

0 

17.78 

71 

21.67 

35 

1.67 

—1 

18.33 

70 

21.11 

34 

1.11 

2 

18.89 

69 

20.55 

33 

0.55 

3 

19.44 

To  convert  deg.  Fahrenheit  to  corresponding  deg.  Centigrade: 
Subtract  32,  multiply  difference  by  5,  and  divide  by  9. 
Example:    Which  degree  Centigrade  corresponds  to  110°  F.?    110  -  82  = 

78;  78  X  5  =  390;  390  -»-  9  =  43.33. 

To  convert  deg.  Centigrade  to  corresponding  deg.  Fahrenheit: 
Multiply  by  «9,  divide  product  by  5,  and  add  32  to  quotient. 
Example:  Which  degree  Fahrenheit  corresponds  to  95.5°  C.?  95.5  X  9  = 

859.5;  859.5  -•-  5  =  171.9;  171.9  -f  32  =  203.6. 


Appendix. 


281 


Table  XV.     Comparison  of  metric  and  customary  weights  and 

measures. 


Customary 
weights  and 
measures. 

Equivalents  in 
metric  system. 

Metric  weights 
and 
measures. 

Equivalents  in 
customary  system. 

1  inch  

2.54  centimeters. 
.3048  meter. 
1.6094  kilometers. 
6.452  sq.  centimeters. 
9.29  sq.  decimeters. 
.836  sq.  meter. 
.4047  hectare. 
16.387cc. 
.0283  cub.  meter. 
.765  cub.  meter. 
.3552  hectoliter. 
29.57  cc. 
.9464  liter. 
3.7854  liters. 
64.8  milligrams. 
28.35  grams. 
.4536  kilogram. 

1  meter  

39.37  inches. 
1.0936  yards. 
.6214  mile. 
.155  sq.  inch. 
10.  764  sq.  feet. 
1.196  sq.  yards. 
2.471  acres. 
.061  cubic  inch. 
61.023  cubic  inches. 
35.314  cub.  feet. 
2.8377  bushels. 
.0338  fluid  ounce. 
1.0567  quarts. 
2.6417  quarts. 
15.43  grains. 
.035274  ounce. 
2.  2046  pounds  (av.) 

1  foot  

1  meter  

1  mile  ..  .. 

1  kilometer.. 

1  square  inch.. 
1  square  foot  .. 
1  square  yard. 
1  acre 

1  sq.  centimeter 
1  square  meter.. 
1  square  meter.. 
1  hectare  

1  cubic  inch... 
1  cubic  foot.... 
1  cubic  yard... 
1  bushel 

1  cc  

1  cub.  decimeter 
1  cub.  meter  
1  hectoliter  
1  cc  

1  fluid  ounce.. 
1  quart 

1  liter. 

1  gallon  

1  decaliter 

1  grain 

1  gram 

1  ounce  (av.).. 
1  pound  (av.  ) 

1  gram  

1  kilogram  

282  Testing  Milk  and  Its  Products. 

SUGGESTIONS  regarding    the  organization  of  co-operative 
creameries    and  cheese    factories. 

When  the  farmers  of  a  neighborhood  are  considering  the 
establishment  of  a  creamery  or  cheese  factory,  they  should  first 
of  all  make  an  accurate  canvas  of  the  locality  to  ascertain  the 
number  of  cows  that  can  be  depended  on  to  supply  the  factory 
with  milk.  The  area  which  may  be  drawn  from  will  vary 
according  to  the  kind  of  factory  which  it  is  de-sired  to  operate. 
A  successful  separator  creamery  will  need  at  least  400  cows 
within  a  radius  of  four  to  five  miles  from  the  proposed  factory.1 
Small  cheese  factories  can  be  operated  with  less  milk,  and 
g  ithered-cream  and  butter  factories  generally  cover  a  much 
larger  territory  than  that  mentioned.  In  all  cases,  however, 
the  question  of  the  number  of  cows  contributing  to  the  enter- 
prise must  be  fully  settled  before  further  steps  are  taken,  since 
this  is  a  point  upon  which  success  will  largely  depend. 

Methods  of  organization.  The  farmers  should  form  their  own 
organization,  and  not  accept  articles  of  agreement  proposed  by 
traveling  agents.  An  agreement  to  supply  milk  from  a  stated 
number  of  cows  should  be  signed  by  all  expecting  to  join  the 
association.  When  a  sufficient  number  of  cows  has  been 
pledged  to  insure  the  successful  operation  of  a  factory,  the  farm- 
ers agreeing  to  supply  milk  should  meet  and  form  an  organi- 
zation. This  may  be  done  according  to  either  of  the  following 
plans  which  have  been  known  to  give  good  satisfaction. 

Raising  money  for  building  and  equipment. 

First. — Each  member  will  sign  an  agreement  to  pay  on  or 
.  before  a  given  date  for  a  certain  number  of  shares  in  the  com- 
pany at dollars  per  share;  or, 

Second. — An  elected  board  of  directors  may  be  authorized  to 

borrow  a  sum  of  money  not  exceeding thousand  dollars 

on  their  individual  responsibility,  and  the  sum  of cents, 

(usually  five  cents)  per  hundred  pounds  of  milk  received  at 
the  factory  shall  be  reserved  for  the  payment  of  this  borrowed 
money. 

iBull.  56,  Wisconsin  experiment  station. 


Appendix.  283 

Constitution  and  by-laws  of  a  co-operative  association  are  drawn 
up  and  signed  by  the  prospective  members  of  the  association 
when  it  has  been  determined  to  form  such  an  association.  It 
is  impossible  to  include  in  an  illustration  all  the  articles  and 
rules  that  may  be  found  useful  in  each  particular  instance;  the 
following  suggestions  in  regard  to  some  of  the  points  to  be  in- 
cluded in  the  documents  are  given  as  a  guide  only.  It  may  be 
found  advisable  to  modify  them  in  various  ways  to  meet  the 
needs  of  the  organization  to  be  formed. 

After  the  constitution  and  by-laws  have  been  drawn  up  and 
made  plain  to  all  the  members  of  the  association,  they  should 
be  printed  and  copies  distributed  to  all  parties  interested. 

CONSTITUTION 

OB 

ARTICLES   OF   AGREEMENT   OF   THE ASSOCIATION.1 

1.  The  undersigned,  residents  within  the  Counties  of , 

State  of ,  hereby  agree  to  become  members  of  the 

Co-operative  Association,   which  is  formed  for  the  purpose  of 
manufacturing  butter  or  cheese  from  whole  milk. 

2.  The  regular  meetings  of  the  association  shall  be  held  an- 
nually on  the day  of  the  month  of. Special 

meetings  may  be  called  by  the  president,  or  on  written  request 
of  one-third  of  the  members  of  the  association,  provided  three 
day's  notice  of  such  meeting  is  sent  to  all  members. 

Meetings  of  the  board  of  directors  may  be  called  in  the  same 
way,  either  by  the  president  or  by  any  two  members  of  the 
board  of  directors. 

3.  Ten  members  of  the  association,  or  three  of  the  board  of 
directors,  shall  constitute  a  quorum  for  the  transaction  of  busi- 
ness. 

4.  The  officers  of  the  association  shall  include  president,  sec- 
retary,  treasurer,  one  of  whom  is  also  elected  manager,  and 
these  officers  together  with  three  other  members  of  the  associa- 

iThe  following  publications  have  been  freely  used  in  preparing  this 
constitution  and  by-laws:  Woll,  Handbook  f.  Farmers  and  Dairymen; 
Minn,  experiment  station,  bull.  No.  35;  Ontario  Agriculture  College,  spec- 
ial bulletin,  May  1897. 


284  Testing  Milk  and  Its  Products.    • 

tion  shall  constitute  the  board  of  directors.  Each  of  these  six 
officers  shall  be  elected  at  the  annual  meeting  and  hold  office 
for  one  year,  or  until  their  successors  have  been  elected  and 
qualified.  Any  vacancies  in  the  board  of  directors  may  be  filled 
by  the  directors  until  the  next  annual  meeting  of  the  association. 

5.  The  duties  of  the  president  shall  be  to  preside  at  all  meet- 
ings of  the  association,  and  perform  the  usual  duties  of  such 
presiding  officers.    He  shall  sign  all  drafts  and  documents  of 
any  kind  relating  to  the  business  of  the  association,  and  pay 
all  money  which  comes  into  his  possession  by  virtue  of  his 
office,  to  the  treasurer,  taking  his  receipt  therefor.    He  shall 
call  special  meetings  of  the  association  when  deemed  necessary. 

In  the  absence  of  the  president,  one  of  the  board  of  directors 
shall  temporarily  fill  the  position. 

6.  The  secretary  shall  attend  all  business  meetings  of  the 
association  and  of  the  board  of  directors  and  shall  keep  a  care- 
ful record  of  the  minutes  of  the  meetings.    He  shall  also  give 
notices  of  all  meetings  and  all  appointments  on  committees, 
etc.    He  shall  sign  all  papers  issued,  conduct  the  correspond- 
ence and  general  business  of  the  association,  and  keep  a  correct 
financial  account  between  the  association  and  its  members.    He 
shall  have  charge  of  all  property  of  the  association  not  other- 
wise disposed  of,  give  bonds  for  the  faithful  performance  of  his 
duties,  and  receive  such  compensation  for  his  services  as  the 
board  of  directors  may  determine. 

7.  The  treasurer  shall  receive  and  give  receipt  for  all  money 
belonging  to  the  association,  and  pay  out  the  same  upon  orders 
signed  by  the  president  and  the  secretary.    He  shall  give  such 
bonds  as  the  board  of  directors  may  require. 

8.  The  board  of  directors  shall  audit  the  accounts  of  the 
association,  invest  its  funds,  appoint  agents,  and  determine  all 
compensations.    They  shall  prescribe  and  enforce  the  rules  and 
regulations  of  the  factory.    They  shall  cause  to  be  kept  a  rec- 
ord of  the  weights  and  tests  of  the  milk  or  cream  received  from 
each  patron,  «,~ae  products  sold,  the  running  expenses,  etc.,  and 
si  all  divide  among  the  patrons  the  money  due  them  each 
month.    They  shall  also  make  some  provision  for  the  with- 


Appendix.  285 

drawal  of  any  member  from  the  association,  and  make  a  report 
in  detail  to  the  association  at  the  annual  meeting.  Such  report 
shall  include  the  gross  amount  of  milk  handled  during  the 
year,  the  receipts  from  products  sold,  and  all  other  receipts,  the 
amounts  paid  for  milk  and  for  running  expenses,  and  a  com- 
plete statement  of  all  other  matters  pertaining  to  the  business 
of  the  association. 

9.  Among  the  rules  and  regulations  to  be  enforced  by  the 
board  of  directors  may  be  included  some  or  all  of  the  following: 

a.  Patrons  shall  furnish  all  the  milk  from  all  the  cows  prom- 
ised at  organization  of  the  association. 

b.  Only  sweet  and  pure  milk  will  be  accepted  at  the  factory, 
and  any  tainted  or  sour  milk  shall  be  refused. 

c.  The  milk  of  each  patron  shall  be  tested  at  least  three  times 
a  mouth. 

d.  Any  patron  proved  to  be  guilty  of  watering,  skimming  or 
otherwise  adulterating  the  milk  sent  to  the  factory,  or  by  tak- 
ing more  than  80  pounds  of  skim  milk  or  whey  for  every  100 
pounds  of  whole  milk  delivered  to  the  factory,  shall  be  fined  as 
agreed  by  the  association. 

e.  A  partron's  premises  may  be  inspected  at  any  time  by  the 
board  of  directors,  or  their  authorized  agent,  for  the  purpose  of 
suggesting  improvements  in  the  methods  of  caring  for  the  milk 
or  the  cows,  in  drainage  and  general  cleanliness;  or  to  secure 
samples  of  the  milk  of  his  cows  for  examination  when  it  is 
deemed  necessary. 

10.  Any  changes  or  amendments  to  the  by-laws  or  constitu- 
tion of  the  association  must  be  made  in  writing  by  the  parties 
proposing  the  same,  and  posted  prominently  in  a  conspicuous 
place  at  the  creamery,  at  least  two  weeks  previous  to  their  being 
acted  upon.     Such  changes  to  be  in  force  must  be  adopted  by  a 
two-thirds  vote  of  the  stockholders. 

11.  In  voting  at  any  annual  or  special  meeting  of  the  asso- 
ciation, the  members  shall  be  entitled  to  one  vote  for  each  cow 
supplying  milk  to  the  factory,  or  for  each  share  of  the  stock 
owned  by  them,  as  agreed  upon. 


INDEX 


The  figures  rkfcr  to  pages  in  the  book. 


Acid  bottle,  Swedish,  47. 

Acid  measures,    31,   46,    54. 

Acid    tester,    Swedish,    67. 

Acidimeter,    Devarda's,    122. 

Acidity  of  cream,  123,  127;  es- 
timation of,  133. 

Acidity  of  milk,  cause  of,  117; 
determination  of,  130,  225; 
methods  of  testing,  118. 

Acidity    pellets,    123. 

Adulteration  of  milk,  109,  113, 
224;  calculation  of,  113. 

Adulterated  butter,  236,  239; 
cheese,  241. 

Albumen,  14;  determination  of, 
in  milk,  223. 

Albuminoids,    13. 

Albumose,    14. 

Alkaline  tablet  test,  122;  stand- 
ard solution  of,  124;  accu- 
racy, 126. 

Alkaline    tabs,    134. 

American   Cheddar   cheese,    21. 

Amphoteric  reaction  of  milk, 
117. 

Analysis,  chemical,  of  butter, 
228;  butter  milk,  226;  cheese, 
240;  condensed  milk,  227; 
cream,  226;  milk,  215;  skim 
milk,  226;  whey,  226. 

Appendix,    255. 

Artificial  butter,  detection  of, 
236. 

Ash,  determination  of,  In  but- 
ter, 229,  230;  in  cheese,  241; 
in  milk,  225. 

Babcock  test,  the,  4,  28;  Bart- 
lett's  modification,  72;  direc- 
tions for,  29;  discussion  of 


details,  37;  for  butter,  94;  for 
butter  milk,  92;  for  cheese, 
95;  for  condensed  milk,  96; 
for  cream,  75,  179;  for  ice- 
cream, 98;  for  skim  milk,  88; 
for  whey,  92;  glassware  used 
in,  37;  modifications  of,  71; 
scales  for  weighing  cream, 
cheese,  etc.,  80;  water  to  be 
used  in,  68. 

Babcock  testers,  54;  electrical, 
63;  hand  testers,  60;  power 
testers,  61;  steam  turbine,  61. 

Bartlett's  modification  of  Bab- 
cock test,  48;  72. 

Bausch  and  Lomb  centrifuge, 
72. 

Beimling    test,    5. 

Bi-carbonate  of  soda,  detection 
.of,  248. 

Bi-chromate  of  potash,  106,  166; 
solution  of,  106. 

Blended  milk,   250. 

Board   of   health   degrees,    104. 

Boiled    milk,    detection    of,    245. 

Boiling  test,   the,   239. 

Boracic  acid,  in  dairy  products, 
133,  247. 

Borax   in   dairy   products,    247. 

B.   &  W.  bottle,  90. 

Butter,  artificial,  12;  detection 
of,  236. 

Butter   chart,    275;    use   of,    196. 

Butter,  20;  artificial,  detection 
of,  236;  Babcock  test  for,  94; 
chemical  analysis  of,  228; 
complete  analysis  in  same 
sample,  230;  composition  of, 
21,  255;  definition,  251;  deter- 
mination of  ash,  229;  casein, 


Index. 


287 


229;  fat,  229;  salt,  236;  water, 
228;  rapid  estimation  of  water, 
231:  Dean's  method,  234; 
Gray's  method,  232;  Irish  test, 
233;  Patrick's  method,  233; 
Wisconsin  high-pressure  oven 
method,  235;  process,  251; 
renovated,  236,  251;  sampling 
for  analysis,  93,  228;  scales 
for  weighing,  93;  standard, 
251;  variations  in  composi- 
tion, 187;  yield,  calculation 
of,  186. 

Butter  fat,  amount  due,  at 
12-25  cents  per  lb.,  269; 
conversion  factor  for,  195; 
definition,  251;  determina- 
tion of  specific  gravity,  237; 
volatile  fatty  acids,  237;  ex- 
pansion coefficient,  36;  price 
per  pound,  202;  specific  grav- 
ity, 38;  determination,  237; 
standard,  251;  table  showing 
amounts  due  for,  at  12  to  25 
cents  per  pound,  269;  test  and 
yield  of  butter,  186. 

Butter  making,  quantities  of 
products  obtained  in,  21. 

Butter  milk,  21;  Babcock  test 
for,  92;  chemical  analysis  of, 
226;  composition,  255;  defini- 
tion, 251;  specific  gravity,  226. 

Calculation  of  adulteration  of 
milk,  113;  of  concentration  of 
condensed  milk,  228;  of  milk 
solids,  107;  of  overrun,  194; 
of  sp.  gr.  of  milk  solids,  111; 
of  yield  of  butter,  186,  192, 
196;  of  cheese,  198;  of  divi- 
dends at  creameries,  202,  204; 
at  cheese  factories,  212;  of 
percentages,  170. 

Calibration  of  glassware,  48; 
Trowbridge  method,  51. 

Carbohydrates,   15. 

Casein,  13;  determination  of,  in 
butter,  229;  in  cheese,  241;  in 
milk,  221;  Hart's  method,  223. 


Centrifugal    machines,    54. 

Chamberland    filters,    14. 

Cheddar  cheese,  American,  21; 
compositimi,  255.  /\^~^ 

Cheese,  21;^^a#?Jtote=*test  ~for, 
95;  calcujs^f»*^eld  of,  from 
casejjfjind^fat,  200;  from  fat, 
l^^rtroinsolids  not  fat  and 

(m#f  199;  composition,  21,  255; 
chemical  analysis  of,  240; 
definitions,  251;  determination 
of  ash;  241;  casein,  241;  fat, 
240;  water,  240;  "filled,"  de- 
tection of,  241;  quality  of, 
from  milk  of  different  rich- 
ness, 210;  sampling,  95; 
standard,  251;  yield,  calcula- 
tion of,  198;  yield  of,  from 
milk  with  2.5  to  6  per  cent, 
fat  and  lactometer  readings 
from  26  to  36,  278;  yield  of, 
and  quality  of  milk,  relation 
between,  199. 

Cheese  factories,  calculating 
dividends  at,  210;  co-opera- 
tive, 213,  282;  proprietary, 
213. 

Cholesterin   in   milk,    18. 

Citric  acid  in  milk,   18. 

Cleaning  solutions  for  test  bot- 
tles, 43. 

Cleaning  test  bottles,  40;  ap- 
paratus for,  41,  44. 

Cochran's    test,    5. 

Coloring  matter  in  milk,  de- 
tection of,  244. 

Colostrum  milk,  18;  composi- 
tion of,  255. 

Composite  samples,  149;  care 
of,  169;  case  for  holding,  165; 
methods  of  taking,  158;  pre- 
servatives for,  166. 

Composite  sampling,  accuracy 
of,  165;  use  of  drip  sample, 
160;  McKay  sampler,  163; 
Michels'  cream  sampling 
tube,  163;  one-third  sample 
pipette,  164;  Scovell  sampling 
tube,  161;  tin  dipper,  158. 


288 


Index. 


Composition  of  butter,  255;  but- 
ter milk,  255;  cheese,  255; 
colostrum  milk,  255;  con- 
densed milk,  255;  cream,  255; 
milk,  18,  255;  milk  ash,  17; 
skim  milk,  255;  whey,  255. 

Condensed  milk,  22;  analysis 
of,  227;  composition  of,  254; 
determination  of  concentra- 
tion, 228;  of  sp.  gr.  of,  228; 
testing  of,  96. 

Control   samples   of  milk,    109. 

Conversion  factor  for  butter 
fat,  195. 

Conversion  tables  for  thermo- 
meter scales,  279;  for  weights 
and  measures,  281. 

Cows,  number  of  tests  required 
in  testing,  145;  single,  sam- 
pling milk  of,  148;  when  to 
test,  147. 

Cream,  19,  226;  acidity  of, 
123,  127;  Babcock  test  for, 
75,  179;  bottles,  the  bulb- 
necked,  79;  the  Winton,  79; 
care  in  sampling,  necessity 
of,  180;  clotted,  251;  defini- 
tion, 251;  determination  of 
acidity  of,  123,  133;  errors  of 
measuring  in  testing,  76;  evap- 
orated, 251;  fat  in  1  to  1000 
Ibs.,  testing  12  to  50  per 
cent.,  267;  gelatin  in,  detec- 
tion of,  245;  overrun,  193;  pas- 
teurized, detection  of,  244; 
scales,  80;  separator,  19;  gath- 
ering and  sampling,  184;  sep- 
aration of,  influence  of  tem- 
perature, 184;  sour,  determina- 
tion of  acidity,  123;  spaces, 
175;  specific  gravity,  77;  stand- 
ard, 251;  starch  in,  246;  test- 
ing, 75;  testing  outfit,  179; 
testing  at  creameries,  175; 
tests,  correct  readings  of, 
85;  use  of  5  cc.  pipette  in 
sampling,  84;  use  of  milk  test 
bottles,  83 -test  bottles,  79; 
calibration,  53;  weight  of,  de- 


livered by  a  17.6  cc.  pipette, 
77. 

Creameries,  calculating  divi- 
dends at,  202;  co-operative, 
204,  282;  cream  testing  at, 
175;  proprietary,  203. 

Creamery  inch,  1,   176. 

Curd  test,  the  Wisconsin  im- 
proved, 135. 

Dean's  method  for  determining 
water  in  butter,  234. 

Definitions  of  milk  and  its 
products,  250. 

DeLaval's   butyrometer,    8. 

Devarda's   acidimeter,   122. 

Diameter  of  tester  and  speed 
required,  relation  between,  57. 

Dividends,  calculating  at  cheese 
factories,  212;  at  creameries, 
202;  of  both  milk  and  cream 
at  the  same  factory,  209. 

Dividers,    use    of,    37. 

Double-necked  test  bottles,  90; 
value  of  divisions  of,  91. 

Draining-rack  for  test  bot- 
tles, 42. 

Eichler's   Sikirepillen,    123. 
Expansion    coefficient   of   butter 
fat,    36. 

Failyer  and   Willard's   test,    4. 

Farrington's  alkaline  tablet 
test,  122. 

Fat,  11;  color  of,  an  index  to 
strength  of  acid  used,  67; 
content,  causes  of  variation 
in,  144;  determination  of,  In 
butter,  229;  in  cheese,  240; 
in  milk,  219;  globules,  11; 
Gottlieb's  method  for  deter- 
mining, 220;  influence  of  tem- 
perature on  separation  of, 
69;  measuring  of,  in  cream 
testing,  85;  in  milk  testing, 
35;  pounds  in  1-10,000  Ibs.  of 
milk,  testing,  3  to  5.35  per 
cent.,  263;  speed  required  for 
complete  separation  of,  59. 


Index. 


289 


Fermentation   test,    the,    137. 
Filled  cheese,   detection  of,   241. 
"Fitch's    Salt   Analysis,"    236. 
Fjord's    centrifugal   cream    test, 

8. 

Fluorids,    detection   of,    248. 
Food,  influence  of  on  quality  of 

milk,    143,    145. 
Food     standards,     Government, 

250. 

Fool  pipettes,   46. 
Formaldehyd,   detection  of,    249. 
Frozen  milk,  sampling  of,    27. 

Gauges   of  cream,   165. 
Gelatine  in  cream,  detection  of, 

245. 
Gerber's     acid-butyrometer,     7; 

fermentation  test,    128. 
Glassware  used  in  the  Babcock 

test,  37;   calibration  of,   48. 
Globulin,   15. 

Glycerids   of  fatty  acids,   13. 
Goat   cheese,    14. 
Gottlieb  method,   the,  220. 
Government      food       standards, 

250. 
Gray's  test  for  water  in  butter, 

232. 
Grain-feeding,    heavy,    influence 

of,  on  quality  of  milk,   153. 

Hand  separator  cream,  gather- 
ing and  sampling,  184. 

Hand  testers,  60. 

Hart's  test  for  casein  in  milk, 
223. 

Hemi-albumose,   14. 

Herd  milk,  variations  in,  151; 
ranges  in  variations  of,  152. 

Hypoxanthin,    18. 

Ice-cream,  test  of,  98;  defini- 
tions, 252. 

Introduction,    1. 

Iowa   station   test,   5. 

Irish  test  for  water  in  butter, 
234. 

Kumiss,    252. 


Lactic  acid  in  milk,   16. 

Lactocrite,    5,    7. 

Lactose,   15. 

Lactochrome,    18. 

Lactometer,  the,  and  its  appli- 
cation, 100;  bi-chromate,  in- 
fluence on,  106;  cleaning  of, 
106;  degrees,  101;  N.  Y.  board 
of  health,  104,  258;  Quevenne, 
101;  reading  the,  104;  testing 
accuracy  of,  106;  time  of  tak- 
ing readings,  105. 

Lecithin  in  milk,   18. 

Leffmann  and  Beam   test,  5. 

Legal  standards  for  milk,  110, 
256. 

Liebermann's    method,    5. 

Macroscopic  impurities  in  milk, 
246. 

Manns'  test,  119;  testing  out- 
fit, 122. 

Marschall  acid  test,  120;  ren- 
net test,  138. 

McKay  sampling  tube,   163. 

Measuring  fat  column  in  test- 
ing cream,  85;  in  testing  milk, 
35. 

Mercury,  calibration  with,  51; 
cleaning,  52. 

Metric  and  customary  systems 
of  weights  and  measures, 
comparison  of,  281. 

Michels'  cream  sampling  tube, 
163. 

Milk,  acidity  of,  117,  130;  albu- 
men in,  12;  adulteration  of, 
109;  amphoteric  reaction  of, 
117;  ash,  composition  of,  17; 
boiled,  detection  of,  245; 
casein  in,  13;  chemical  analy- 
sis of,  215;  cholesterin  in,  18; 
churned,  sampling  of,  24;  cit- 
ric acid  in,  18;  colostrum,  18; 
composition  of,  10,  18;  table 
showing  composition  of,  255; 
composite  sampling  of,  158; 
condensed,  22,  96,  254;  correc- 
tion table  for  specific  grav- 


290 


Index. 


ity,  259;  definitions,  250;  de- 
tection of  coloring  matter, 
244,  of  preservatives,  133, 
247;  determination  of  acidity, 
130,  225;  of  ash,  225;  of  casein 
and  albumen,  221;  of  fat,  219; 
of  milk  sugar,  224;  of  solids, 
219;  of  specific  gravity,  216; 
of  water,  218;  fat  in,  11;  fat 
available  for  butter  in  differ- 
ent grades  of,  192;  from  cows 
in  heat,  110;  from  sick  cows, 
110;  from  single  cows,  sam- 
pling of,  148;  variations  in, 
140;  frozen,  sampling  of,  27; 
gases,  18;  hypoxanthin,  18; 
lactochrome,  18;  lactose,  15; 
lecithin,  18;  legal  stand- 
ards, 110,  256;  macroscopic 
impurities,  246;  mineral 
components,  17;  partially 
churned,  sampling  of,  24; 
pasteurized,  detection,  244; 
preservatives,  detection,  247; 
quality  of,  influence  of  food, 
155;  of  heavy  grain  feeding, 
153;  of  pasture,  154;  method 
of  improving,  156;  sampling. 
23,  29;  scale,  Richmond's,  108; 
scales,  139;  serum,  10;  skim- 
ming, 113;  solids,  10;  calcu- 
lation of,  107;  specific  grav- 
ity of,  111;  souring  of,  15; 
sour,  sampling  of,  26;  stand- 
ards, 102,  250;  sugar,  15; 
tests  for  adulteration:  nitric 
acid  test,  242;  sp.  gr.  of 
skim  milk,  milk  serum,  or 
whey,  242;  testing  on  the 
farm,  140;  testing  purity  of, 
135;  urea,  18;  water,  11; 
watering  of,  114;  watering 
and  skimming,  114. 

Milk  test,  a  practical,  need  of, 
1;  requirements  of,  6;  bottle, 
use  of,  In  testing  cream,  83; 
Russian,  71. 

Milk  tests,  Babcock,  4,  6;  Beim- 
linp:  (L,effmann  and  Beam),  5; 


Cochran,  5;  DeLaval  butyro- 
meter,  8;  Failyer  and  Wil- 
ward,  4;  Fjord,  8;  foreign,  7; 
Gerber  acid-butyrometer,  7; 
introduction  of,  4;  lactocrite, 
5,  7;  Liebermann,  5;  Lind- 
strom,  9;  Nahm,  5;  Parson, 
5;  Patrick  (Iowa  station  test), 
5;  Rose -Gottlieb,  5,  220;  sal- 
method,  5;  Schmied,  5;  Short, 
4;  sin-acid,  5;  Thorner,  5; 
Wollny  refractometer,  9. 

Milk  products,  composition  of, 
19,  255. 

Monrad   rtennet    test,    the,    138. 

Milk  testing,  28;  on  the  farm, 
140. 

Nahm's    test,    5. 

N.  Y.  board  of  health  lacto- 
meter, 104;  degrees  corre- 
sponding to  Quevenne  lacto- 
meter degrees,  258. 

Nitric  acid  test  for  adulteration 
of  milk,  242. 

Non-fatty  milk  solids,   10. 

Normal  solutions,  119. 

Nuclein,    14. 

Oil-test   churn,   2,    176. 

Ohlsson  test  bottle,   90. 

Oleomargarine,  detection  of, 
239;  cheese,  detection  of,  241; 
tests  for  artificial  coloring 
matter  in,  240. 

One-third  sampling  pipette,  use 
of,  164. 

Organization  of  co-operative 
creameries  and  cheese  fac- 
tories, suggestions  concern- 
ing, 282. 

Overrun,  189;  calculation  of, 
194;  factors  influencing,  189; 
table,  198,  277;  from  cream, 
193;  from  milk,  189. 

Parsons'   test,   5. 
Pasteurized  milk  or  cream,  de- 
tection   of,    244, 


Index. 


291 


Pasture,  influence  on  quality  of 
milk,  154. 

Patrick's  test,  5;  method  for 
determining  water  in  butter, 
233. 

Patron's   dilemma,    a,    172. 

Percentages,  average,  methods 
of  calculation,  171;  fallacy  of 
averaging,  170. 

Phenolphtalein,  120. 

Physician's  centrifuge,  use  of, 
in  milk  testing,  72. 

Pipettes,  30,  45;  proper  con- 
struction of  points,  45;  proper 
method  of  emptying,  31;  cali- 
bration, 54. 

Pooling  system,    3. 

Potassium   bi-chromate,    166. 

Power  testers,   61. 

Preservaline,  133,  247;  detec- 
tion of  in  milk,  133. 

Preservatives,  for  composite 
samples,  166;  in  milk,  detec- 
tion of,  133,  247. 

Primost,    14. 

Process  butter,  detection  of, 
239. 

Proteose,    14. 

Quevenne  lactometer,  the,  101; 
degrees  corresponding  to 
scale  of  N.  Y.  board  of  health 
lactometer,  104,  258. 

Readings  of  cream  tests,  85; 
of  milk  tests,  35. 

Recknagel's  phenomenon,   105. 

Refractometer,   9. 

Reichert  number,    239. 

Reichert-Wollny  method,    237. 

Relative-value   tables,    208,    271. 

Rennet  tests,   138. 

Renovated  butter,  detection  of, 
239;  boiling  test,  239;  Water- 
house  test,  239. 

Reservoir  for  water  in  Babcock 
test,  70. 

Richmond's  milk  scale,   108. 

R5se -Gottlieb  method,   5,   220. 

Russian   milk   test,   the,   71. 


Salicylic  acid,  detection  of,  248. 

Salt,    estimation   in   butter,    236. 

Sampling  cheese,  95;  milk,  23, 
29;  milk  from  single  cows, 
148. 

Sampling  tube,  for  cream,  179; 
McKay,  163;  Michels,  163; 
Scovell,  161. 

Scales  for  weighing  cream,  80; 
milk,  148. 

Schmied  method,   the,  5. 

Scovell  sampling  tube,    161. 

Serum  solids,   10. 

Short's    test,    4. 

Siegfeld's  modification  of  Bab- 
cock  test,  72. 

Sinking  fund,    206.      • 

Separator    cream,    19. 

Skimming  of  milk,  detection  of, 
113. 

Skim  milk,  19;  Babcock  test 
for,  88;  chemical  aanalysis  of, 
226;  composition  of,  255;  con- 
densed, 250;  definition,  250; 
sp.  gr.,  100;  test  bottles,  90, 
92. 

Solids  not  fat,  10;  formulas  for 
calculating,  108;  tables  show- 
ing, corresponding  to  0-6  per 
cent,  fat  and  26-36  lactometer 
degrees,  260. 

Sour  milk,  sampling,  26;  analy- 
sis, 226. 

Space   system,    the,    175. 

Specific  gravity,  100;  cylinders, 
101,  105;  influence  of  tem- 
perature, 102;  of  butter  fat, 
determination  of,  237;  of  but- 
ter, milk,  226;  of  condensed 
milk,  228;  of  milk,  216;  of 
milk  solids,  111;  of  sour  milk, 
226;  temperature  correction 
table,  259. 

Speed  required  for  complete 
separation  of  fat,  57;  ascer- 
taining necessary  speed,  59. 

Spillman's    cylinder,    129. 

Standard  measure  for  calibrat- 
ing test  bottles,  50. 


292 


Index. 


Standards  of  purity,  Govern- 
ment, for  milk  and  its  prod- 
ucts, 250. 

Starch    in    cream,    246. 

Steam   turbine   testers,   61. 

Stokes'  acidity  pellets,   123. 

Storch's     test,     245. 

Sulfuric  acid,  64;  table  show- 
ing strength  of,  67;  testing 
strength  of,  65. 

Sweetened   condensed   milk,    96. 

Swedish    acid    bottle,    47. 

Swedish   acid   tester,   67. 

Tank  for  cleaning  test  bottles, 
43. 

Temperature  of  turbine  test- 
ers, 36;  of  fat  when  tests  are 
read,  36. 

Test  bottles,  30,  37;  apparatus 
for  cleaning,  41,  44;  bulb- 
necked  cream,  78;  calibra- 
tion, 48;  cleaning,  40;  cream, 
79;  double -necked,  79;  drain- 
ing-rack  for,  42;  marking,  39; 
for  cream  testing,  79;  for 
skim  milk  testing,  90,  92; 
rack  for  use  in  creameries 
and  cheese  factories,  165; 
tank  for  cleaning,  43;  Winton 
cream,  79. 

Testers,  54;  ascertaining  speed 
of,  58;  electrical,  63;  hand, 
60;  power,  61. 

Testing  cows,  number  of  tests 
required  during  a  period  of 
lactation,  145. 

Testing  milk  and  its  products, 
1;  on  the  farm,  140. 

Test  sample,   size   of,   151. 

Tests  of  cows,   official,    148. 

Thermometer  scales,  compari- 
son of,  279. 

Thorner's    method.    5. 

Total  solids  in  milk,  10;  deter- 
mination, 219. 

Trowbridge  method  of  calibra- 
tion, 49. 

Turbine  testers,  61;  hot,  er- 
rors In,  36. 


Variation  in  composition  of 
butter,  187;  in  quality  of  milk, 
140,  151;  causes  of,  144;  lati- 
tude of,  110;  ranges  in,  for 
herd  milk,  152. 

Volatile  acids  in  butter  fat, 
determination,  237. 

Wagner    skim    milk    bottle,    92. 

Waste  acid  jar,  40. 

Water,  calibration  with,  48;  de- 
termination of,  in  butter,  228; 
in  cheese,  240;  in  milk,  218, 
219;  reservoir  for,  70;  to  be 
used  in  the  Babcock  test, 
69. 

Waterhouse   test,    239. 

Watering  of  milk,  detection 
of,  114;  watering  and  skim- 
ming, detection  of,  114. 

Weights  and  measures,  com- 
parison of  metric  and  cus- 
tomary, 281. 

Westphal   balance,    217.  i^ 

Whey,  22;  Babcock  test  for,  92; 
chemical  analysis,  226;  composi- 
tion, 255;  defl nation,  252. 

Winton    cream    bottle,    the,    79. 

Wisconsin  creamery  butter, 
summary  of  analyses,  188. 

Wisconsin  curd  test,  the  im- 
proved, 135. 

Wisconsin  high-pressure  oven 
test,  for  water  in  butter,  235. 

Wollny   refractometer,    9. 

World's  Fair  breed  tests,  com- 
position of  butter  from,  187; 
variation  in  quality  of  milk, 
152. 

Yield  of  butter,  calculation  of, 
186.  and  butter  fat  test,  186; 
from  different  grades  of  milk, 
192,  196;  table  showing,  from 
1  to  10.000  Ibs.  of  milk,  test- 
ing 3  to  5.3  per  cent.,  275. 

Yield  of  cheese,  calculation  of, 
198;  relation  between,  and 
quality  of  milk,  199;  table 
showing,  corresponding  to  2.5 
to  6  per  cent,  of  fat,  with 
lactometer  readings  of  26  to 
36,  278. 


NEW  19O8 

DE LAVAL 

CREAM 

SEPARATORS 


January  1,  1908  marks  another  great  move  forward  in  the 
development  of  the  Cream  Separator — the  introduction  of  a 
complete  new  line  of  DE  LAVAL  Farm  and  Dairy  Sizes  of 
machines,  ranging  in  separating  capacity  from  135  Ibs.  to  1350 
Ibs.  of  milk  per  hour. 

As  nearly  perfect  as  the  DE  LAVAL  machines  have  been 
before,  they  are  now  still  further  improved  in  practically  every 
detail  of  construction  and  efficiency,  and  every  feature  reflects 
the  past  two  years  of  experiment  and  test  by  the  De  Laval 
engineers  and  experts  throughout  the  world. 

The  principal  changes  are  in  greater  simplicity  of  con- 
struction, ease  of  cleaning  and  replacement  of  parts;  less  cost 
of  repairs  when  necessary;  easier  hand  operation;  more  com- 
plete separation  under  hard  conditions;  greater  capacity,  and  a 
material  reduction  of  prices  in  proportion  to  capacity. 

The  DE  LAVAL  was  the  original  Cream  Separator  and  for 
thirty  years  it  has  led  in  making  every  new  separator  invention 
and  improvement.  Every  good  feature  is  now  bettered  and 
retained  and  many  new  and  novel  ones  added,  rendering 
DE  LAVAL  superiority  over  imitating  machines  even  greater 
in  every  way  than  ever  before. 

A  new  1908  DE  LAVAL  catalogue  and  any  desired  par- 
ticulars are  to  be  had  for  the  asking. 

THE  DE  LAVAL  SEPARATOR  Co. 


RANDOLPH  &  CANAL  STS. 

CHICAGO 
1213  &  1215  FILBERT  ST. 

PHILADELPHIA 

DRUMM  &  SACRAMENTO  STS. 

SAN  FRANCISCO 


General  Offices : 

74  CORTLANDT  STREET, 

NEW  YORK. 


173-177  WILLIAM  STREET 

MONTREAL 
14  &  16  PRINCESS  STREET 

WINNIPEG 

IO7  FIRST  STREET 

PORTLAND,  OREG. 


WIZARD  TURBINE 
BABCOCK    TESTERS 

Complies  with  the  strictest  requirements  of 
milk  testing  authorities;  turbine  on  top  in  separ- 
ate case;  spring  brake  for 
stopping;t  wo  bearings  in- 
sure freedom  from  vibra- 
tion, heating  controlled 
by  damper  in  exhaust  out- 
let.The  same  high-grade 
construction  may  be  had 
in  theTwentieth  Century 
Hand  Tester.  The  ^Of- 
ficial" is  a  2  and  4  bottle 
hand  tester  for  farm  use. 
Write  for  full  descrip- 
tion and  prices. 


Creamery  Package  Mfd-  Co., 


TKe    Farrington    Moisture    Test 

(Wisconsin  High-Pressure  Oven  Principle) 

Consists  of  an  insulated  high-pressure  oven  fitted  fon»connecting 
direct  to  a  steam  line  in  your  creamery;  four  sample  dishes,  lifter 
and  a  special  moisture  per  cent.  scale.  The  oven  is  handsomely 
finished  in  oxidized  copper  and  is  an  ornament  to  any  creamery.  The 
steam  compartments  are  tested  to  100  Ibs.  pressure  before  assem- 
bling and  the  outfit  has  "quality'  '  as  well  as  "looks". 

The  scale  is  a  Torsion  Balance  with  moisture  per  cent  beams, 
which  does  away  with  calculations  and  errors.  It  is  sensitive  to 
1-300  of  a  gram. 

Take  it  all  in  all  it's  a  moisture  test  worth  while.  We  particu- 
larly want  to  sell  them  to  people  who  would  appreciate  a  moisture 
test  that  is  something  better  than  a  guessing  machine.  If  you're 
interested  in  it,  let  us  quote  you  prices. 

Oven  and  scales  will  be  sold  separate  if  you  want  them  that  way 
but  if  you  want  the  best  moisture  test,  get  the  complete  outfit. 

CREAMERY  PACKAGE  MFG.  CO.,  Chicago,  111. 


THE    "FACILE" 

Iron  Frame  Babcock  Milk  Testers 


FACILE  JR.  TESTER 
Two  Bottle 


FACILE  STEAM  TURBINE  TESTER 
24  Bottle 


FACILE  HAND  TESTER 
Sizes  6, 8, 10  and  12  Bottle 


D.   H.  Burrell  &  Co.,  Little  Falls,  N.  Y. 

Creamery,  Cheese  Factory  and  Dairy  Apparatus  and  Supplies 
SEND  FOR  CATALOGUE 


The  Tubular  Cream  Separator 

Different  from  All  Others 


Low     Supply     Tank 
Suspended  Bowl 
Perfect  Self  Oiling 
Bottom    Feed 
Fewest    Bowl     Parts 
Quickest  Gleaned 

No  Exposed  Gear 
No  Oil  Cups  or  Holes 
Plain  Smooth  Bowl 
Waist-lowCranfcshaft 
No  Bowl  Vibration 
Least    Weight    Bowl 


Above  are  some  reasons  why  the  Tubular  is  different  from  and 
better  than  other  cream  separators,  why  it  is  in  a  class  alone,  why 
it  belongs  to  the  XXth  Century,  while  others  are  of  the  XlXth. 

They  are  plain  reasons,  which  your  own  eyes  may  prove,  if  you 
carefully  look  at  and  compare  separators. 


The  Sharpies  Separator  Co. 

West  Chester,    Pennsylvania 

Toronto,  Canada  Chicago,   Illinois 


The   "World's    Record"    Test 


Of  Skimmilk  was  made  at  the  Pan-American  Exposition 
"Model  Dairy"in  Buffalo.  N.Y., 1901,  when  the  improved 

U.  S.  CREAM  SEPARATOR 

established  and  has  since  held  the  present 
World's  Record  for    Cleanest    Skimming 

by  averaging  in  50  consecutive  runs  to  leave  25  per  cent 
LESS  butter  fat  in  the  sklmmilk  than  its  nearest  com- 
petitor. This  record  was  never  equaled  until  at  the 
Lewis  &  Clarke  Exposition,  the  U.  8.  lowered  its  own 
World's  Record  in  a  three  days' composite  test  of  the 
separated  milk  from  all  the  cows  of  all  the  dairy  herds 
at  the  Exposition.  This  was  even 
a  harder  tost  than  the  famous 
Pan- American  run. 


As  the  test  at  the  Pan- Amer- 
ican Exposition  is  the  last  ac- 
tual, protracted,  public,  na- 
tional and  international  test 
— the  U.  S.  continues  to  main- 
tain indisputable  right  to  the 
title  of  the  Best  and  Most 
Efficient  Machine  of  its  kind. 


The  U.  S.  has  been  on  the 
market  sixteen  years.  Its  re- 
liability is  a  proved  fact.  It  is 
built  by  the  same  Company  that 
manufactures  the  popular 
"Agos"  Babcock  testers  shown 
on  pages  60  and  63. 


The  U.  S.  is  also  the  simplest,  strongest,  safest  sep- 
arator. Only  two  parts  in  the  bowl— easy  to  wash- 
saves  time  and  work.  Gears  run  in  oil  and  turn  easy, 
fiood  for  a  lifetime  of  service  with  ordinary  care.  Let 
us  tell  you  all  about  it. 

Just  write,  "Send  me  new  Illustrated  Catalog." 
The  thirty  pictures  tell  ihe  story.  Free  to  you.  Write 
today,  mentioning  this  book  and  address 


VERMONT  FARM  MACHINE  COMPANY 
BELLOWS  FALLS,  VERMONT,   U.  S.  A. 

Eighteen    Distributing  Warehouses 


Chr.  Hansen's 
Laboratory 

Headquarters      for 
Dairy  Preparations  Unequaled    in    Purity  and   Strength 

Chr.  Hansen's  Danish  Rennet  Extract 
Ghr.  Hansen's   Danish  Cheese  Color 

VEGETABLE  BUTTER  COLOR  and  LACTIC 
FERMENT   CULTURE 

Rennet  Tablets  and  Cheese  Color  Tablets  for  Cheese- 
Making  on  the  Farm 

Special  Junket  Cream  Tablets  for  Ice  Cream  Mfrs. 
Junket  Tablets,  Pure  Food  Colors  and  Flavoring  Extracts 

CHR.  HANSEN'S  LABORATORY 

Box  1031  LITTLE  FALLS,  NEW  YORK 


Electric  Babcock  Testers 


See  Page  63  of  This  Book 

Dry,  Glean 
Convenient 


Bui.  706 


Board  of  Health 
Centrifuge  for 
Bacteria  Test 


Bui.  705 


International 
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CAMBRIDGE,  MASS. 


PDCAMU/CIPUIWP    Q  P  A  I  C    For  Use  in   Connection 
UnLHlVI-ff  LlUniHU    OUALC    with  the    Babcock  Test 

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in.  long;  porcelain  plates  3 in.  square. 
Manufactured  by 

Price  $10  710  Market  St.,  Philadelphia,  Pa.  HENRY  TROEMMER 


Woll's  Book  on  Silage 

Is  the  best  book  yet  published  on 
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ceipt of  One  Dollar.  ::  :: 

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1                   LIBRARY,  BRANCH  OP  THE  COLLEGE  OF  AGRICULTURE 

"W\                                                  UNIVERSITY  OP  CALIFORNIA             5m-8,'37(s) 

CrLi&,    wu^ani^    .,,%.     VM.M.X.       otrucmxi    «-<i       C7ea     \IUIIH-V 

la.,'  1901,    193    pp  .              ,                 °  00 

King,    The    Physics    of    Agriculture,      Second    ed  ,    Madi- 

Son,    Wis.,    1901,    604    pp  175 

MENDOTA    BOOR    CO.,     Madison,    Wisconsin 

Call  Number: 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


